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At least 19 recordsLinked to original sources
PubMed1979

Identification of organic phosphorus covalently bound to collagen and non-collagenous proteins of chicken-bone matrix. The presence of O-phosphoserine and O-phosphothreonine in non-collagenous proteins, and their absence from phosporylated collagen.

Non-collagenous phosphoproteins, almost all of which can be extracted in EDTA at neutral pH in the presence of proteinase inhibitors, are identified in the matrix of chicken bone, and are therefore not covalently bound to collagen. Similarly, all the peptides containing gamma-carboxyglutamic acid are present in the EDTA extract and none in the insoluble residue, confirming that none is covalently linked to chicken bone collagen. However, organic phosphorus is also found to be present in chicken bone collagen, principally in the alpha2-chains. Of the total protein-bound organic phosphorus present in chicken bone matrix, approx. 80% is associated with the non-collagenous proteins and 20% with collagen. The soluble non-collagenous proteins contain both O-phosphoserine and O-phosphothreonine and these account for essentially of their organic phosphorus content. In contrast, collagen contains neither O-phosphoserine nor O-phosphothreonine. Indeed, no phosphorylated hydroxy amino acid, phosphoamidated amino acid or phosphorylated sugar could be identified in purified components of collagen, which contain approximately four to five atoms of organic phosphorus per molecule of collagen. Peptides containing organic phosphorus were isolated from partial acid hydrolysates and enzymic digests of purified collagen components, which contain an as-yet-unidentified cationic amino acid. These data, the very high concentrations of glutamic acid in the phosphorylated peptides, and the pH-stability of the organic phosphorus moiety in intact collagen chains strongly suggest that at least part of the organic phosphorus in collagen is present as phosphorylated glutamic acid. This would indicate that the two major chemically different protein fractions in chicken bone matrix that contain organic phosphorus may represent two distinct metabolic pools of organic phosphorus under separate biological control.

1-Carboxyglutamic Acid↗
PubMed1986

In vitro formation of hybrid fibrils of type V collagen and type I collagen. Limited growth of type I collagen into thick fibrils by type V collagen.

Type V collagen and type I collagen were obtained from human placentas by pepsin treatment, followed by salt fractionation. The precipitates formed at 37 degrees C from a mixed solution of type V collagen and type I collagen, reacted with antibodies to either type V collagen or type I collagen. The precipitates seen by electron microscopy were fine flexible fibrils, with a D-periodic banding pattern. The average diameter of hybrid fibrils was smaller than 50 nm, when the proportion of type V collagen exceeded that of type I collagen. Type V collagen directly interacts with type I collagen in forming hybrid fibrils, resulting in limitation of the growth of type I collagen fibrils into thicker fibrils. We propose that the fibrils with a predominant type V collagen content may occur in the pericellular environment of various tissues, as a basic structure in connecting basal laminae with interstitial collagen fibrils.

Chemical Precipitation↗
PubMed1997

Complete primary structure of two splice variants of collagen XII, and assignment of alpha 1(XII) collagen (COL12A1), alpha 1(IX) collagen (COL9A1), and alpha 1(XIX) collagen (COL19A1) to human chromosome 6q12-q13.

Overlapping cDNA clones that encode the full-length human alpha 1(XII) collagen polypeptides were isolated. The long variant molecule cDNA of 9750 nucleotides (nt) contains a 9189-nt open reading frame encoding 3063 amino acid residues. The short variant molecule cDNA of 6258 nt contains a 5697-nt open reading frame encoding 1899 amino acid residues. At the amino terminus of each variant is a 24-residue signal peptide that is followed by the mature polypeptides of 3039 amino acid residues with a calculated molecular mass of 330,759 Da for the long variant and 1875 amino acid residues with a calculated molecular mass of 203,163 Da for the short variant polypeptide. The human collagen XII chains are predicted to have all the structural domains described for the molecules in chicken and mouse, including, fibronectin type III repeats, von Willebrand factor A domains, and two triple-helical domains similar to those of all the other collagen family members. The amino acid residue sequence of human alpha 1(XII) collagen showed 92% identity to the mouse chain and 78% identity to the chicken chain. The sequence of three peptide fragments of collagen XII isolated from human placenta was identical to the sequence predicted from the deduced cDNA sequence and confirms that the cDNA encodes human alpha 1(XII) collagen. An isolated genomic clone was used to map the locus of the COL12A1 gene to chromosome 6q12-q13, very close to the locus of the FACIT collagen genes COL9A1 and COL19A1. RT-PCR on a variety of cDNAs demonstrates that both variant transcripts appear in human amnion, chorion, skeletal muscle, small intestine, and in cell cultures of human dermal fibroblasts, keratinocytes, and endothelial cells. Only the small variant transcript is apparent in human lung, placenta, kidney, and a squamous cell carcinoma cell line. These results confirm the previous observations showing that collagen XII is found in collagen I-containing tissues.

Alternative Splicing↗
PubMed2001

Regeneration of canine peroneal nerve with the use of a polyglycolic acid-collagen tube filled with laminin-soaked collagen sponge: a comparative study of collagen sponge and collagen fibers as filling materials for nerve conduits.

A novel artificial nerve conduit was developed and its efficiency was evaluated on the basis of promotion of peripheral nerve regeneration across an 80-mm gap in dogs. The nerve conduit was made of a polyglycolic acid-collagen tube filled with laminin-soaked collagen sponge. Conduits filled with either sponge- or fiber-form collagen were implanted into an 80-mm gap of the peroneal nerve (five dogs for each form). Twelve months postoperatively nerve regeneration was superior in the sponge group both morphometrically (percentage of neural tissue: fiber: 39.7 +/- 5.2, sponge: 43.0 +/- 4.5, n=3) and electrophysiologically (fiber: CMAP 1.06 +/- 0.077, SEP 1.32 +/- 0.127 sponge: CMAP 1.04 +/- 0.106, SEP 1.24 +/- 0.197, n=5), although these differences were not statistically significant. The observed regeneration was complementary to successful results reported previously in the same model, in which collagen fibers exclusively were used. The results indicate a possible superiority of collagen sponge over collagen fibers as filling materials. In addition, the mass-producibility, superior scaffolding potential, and capacity for gradual release of soluble factors of the sponge provide make it an attractive alternative to fine fibers, which are both technologically difficult and costly to produce. This newly developed nerve conduit has the potential to enhance peripheral nerve regeneration across longer gaps commonly encountered in clinical settings.

Animals↗
PubMed1992

The fibrillar collagens, collagen VIII, collagen X and the C1q complement proteins share a similar domain in their C-terminal non-collagenous regions.

A sequence comparison of the C-termini of collagens X, VIII, the collagen-like complement factor C1q, and the fibrillar collagens showed a conserved cluster of aromatic residues. This conserved cluster was in a domain of approximately 130 amino acids that exhibited marked similarities in hydrophilicity profiles between the different collagens, despite a low level of sequence similarity. These data suggest that the 'collagen X-like family' and the fibrillar collagens contain a domain within their C-termini that adopts a common tertiary structure, and that a conserved cluster of aromatic residues in this domain may be involved in C-terminal trimerization.

Amino Acid Sequence↗
PubMed1989

The cloning and sequencing of alpha 1(VIII) collagen cDNAs demonstrate that type VIII collagen is a short chain collagen and contains triple-helical and carboxyl-terminal non-triple-helical domains similar to those of type X collagen.

We have isolated two overlapping cDNA clones covering 2425 base pairs encoding a short type VIII collagen chain synthesized by rabbit corneal endothelial cells. The cDNAs encode an open reading frame of 744 amino acid residues containing a triple-helical domain of 454 residues flanked by 117- and 173-residue amino and carboxyl non-triple-helical domains (called NC2 and NC1, respectively). Based on the identity between the DNA-derived amino acid sequence and the amino acid sequence of a type VIII collagen CNBr peptide obtained from rabbit corneal Descemet's membrane, we conclude that the cDNAs code for a type VIII collagen chain. We give this chain the designation alpha 1(VIII). The alpha 1(VIII) triple-helical domain contains eight imperfections in the Gly-X-Y repeated structure with Gly-X instead of a full triplet. The length of the triple-helical domain and number and relative locations of these imperfections are remarkably similar to those of chicken alpha 1(X) collagen. The amino acid sequence of the carboxyl three-quarters of the NC1 domain has high sequence similarity to that of alpha 1(X) collagen. These data suggest that the triple-helix coding portions and carboxyl three-quarters of the NC1 domains of the alpha 1(VIII) and alpha 1(X) genes have a common evolutionary origin.

Amino Acid Sequence↗
PubMed2002

Interventions for treating collagenous colitis.

BACKGROUND: Collagenous colitis is a disorder that is recognized as a cause of chronic diarrhea. Treatment has been based mainly on anecdotal evidence. This review was performed to identify therapies for collagenous colitis that have been proven in randomized trials. OBJECTIVES: To determine effective treatments for patients with clinically active collagenous colitis. SEARCH STRATEGY: Relevant papers published between 1970 and January 2002 were identified via the MEDLINE, PUBMED, and EMBASE databases. Manual searches from the references of identified papers, as well as review papers on collagenous or microscopic colitis were performed to identify additional studies. Abstracts from major gastroenterological meetings were searched to identify research submitted in abstract form only. Finally, the Cochrane Controlled Trials Register and the Cochrane Inflammatory Bowel Disease Group Specialized Trials Register were searched for other studies. SELECTION CRITERIA: Four randomized trials were identified. One trial studied bismuth subsalicylate (published in abstract form only), and 3 trials (2 published in abstract form only) studied budesonide in the therapy of collagenous colitis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by each author onto 2x2 tables (treatment versus placebo and response versus no response). For therapies assessed in one trial only, p-values were derived using the chi-square test. For therapies assessed in more than one trial, summary test statistics were derived using the Peto odds ratio and 95% confidence intervals. Data were combined for analysis only if the outcomes were sufficiently similar in definition. MAIN RESULTS: There were 9 patients with collagenous colitis in the trial studying bismuth subsalicylate (nine 262 mg tablets daily for 8 weeks). Those randomized to active drug were more likely to have clinical (p=0.003) and histological (p=0.003) improvement than those assigned to placebo. A total of 86 patients were enrolled in 3 trials studying budesonide (9 mg daily for 6 to 8 weeks). The pooled odds ratio for clinical response to treatment with budesonide was 16.79 (95% CI 7.28-38.74), with a number needed to treat of 2 patients. There was significant histological improvement with treatment in all 3 trials studying budesonide therapy. REVIEWER'S CONCLUSIONS: Budesonide is effective in the treatment of collagenous colitis. The evidence for bismuth subsalicylate is weaker, but still important. The roles of these and other therapies in inducing or maintaining remission (as opposed to clinical or histological improvement) of collagenous colitis are unknown.

Anti-Inflammatory Agents↗
PubMed1997

Modulation of collagen gene expression by cytokines: stimulatory effect of transforming growth factor-beta1, with divergent effects of epidermal growth factor and tumor necrosis factor-alpha on collagen type I and collagen type IV.

Transforming growth factor-beta1 (TGF-beta1) is well recognized as a potent mediator of both fibrillar (collagen type I) and basement membrane (collagen type IV) production. However, tissue injury is characterized by the concomitant expression of many cytokines and/or growth factors in addition to TGF-beta1, and the ultimate extent of extracellular-matrix (ECM) deposition may reflect the interacting effects of TGF-beta1 and these other cytokines and/or growth factors. We, therefore, sought to determine whether other cytokines and/or growth factors, known to be produced after tissue injury, are capable either alone or in combination with TGF-beta1 of modulating collagen gene expression. Collagen type I and collagen type IV gene expression was assessed in NIH-3T3 cells, a murine fibroblast-like cell line that responds to TGF-beta1, with increases in both collagen type I and collagen type IV production. TGF-beta1 coordinately induced production of collagen type IV messenger ribonucleic acid (mRNA) to a level 3.8-fold above its baseline value (p < 0.001) and collagen type I mRNA to a level 2.6-fold above its baseline value (p < 0.001). Of the other cytokines and/or growth factors tested, only epidermal growth factor (EGF) had significant effects on collagen mRNA expression. We report the novel observation that EGF significantly induced collagen type IV mRNA (3.0-fold; p < 0.001) but did not alter collagen type I mRNA expression. Platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and insulin-like growth factor-1 (IGF-1) did not alter the expression of mRNA for collagen type IV or collagen type I. Addition of TGF-beta1 to cytokine- and/or growth factor-treated cells increased both collagen type IV and collagen type I mRNA levels. However, collagen type IV mRNA levels were similar in cultures given TGF-beta1 alone and cultures given TGF-beta1 with other cytokines and/or growth factors; there were no additive, synergistic, or antagonistic effects after coadministration of TGF-beta1 and other cytokines and/or growth factors. With regard to collagen type I mRNA expression, all cytokines and/or growth factors tested, with the exception of TNF-alpha, had no effect on collagen type I mRNA levels in TGF-beta1-treated cultures. Importantly, TNF-alpha antagonized the stimulatory effect of TGF-beta1 on collagen type I mRNA levels. These observations support a dominant role for TGF-beta1 in stimulating coordinate expression of collagen type I and collagen type IV mRNAs by NIH-3T3 cells; EGF and TNF-alpha are capable of inducing divergent expression of the genes for these two types of collagen.

3T3 Cells↗
PubMed2002

Analysis of the interaction of platelet collagen receptor glycoprotein VI (GPVI) with collagen. A dimeric form of GPVI, but not the monomeric form, shows affinity to fibrous collagen.

Glycoprotein VI (GPVI) is a platelet-specific glycoprotein that has been indicated to react with collagen and activate platelets. Its structure was recently identified by cDNA cloning (Clemetson, J. M., Polgar, J., Magnenat, E., Wells, T. N., and Clemetson, K. J. (1999) J. Biol. Chem. 274, 29019-29024). However, the mechanism of the interaction between collagen and GPVI has not been analyzed in detail because both collagen and GPVI are insoluble molecules. In this study, we expressed the extracellular domain of GPVI as soluble forms as follows: the monomeric form (GPVIex) and the dimeric form of GPVI fused with the human immunoglobulin Fc domain (GPVI-Fc(2)). Purified GPVIex strongly inhibited convulxin (Cvx)-induced platelet aggregation but only weakly inhibited that induced by collagen-related peptide. However, only GPVI-Fc(2), and not GPVIex, inhibited collagen-induced platelet aggregation. The dimeric form of GPVI exhibits high affinity for collagen, as concluded from measurements of GPVI binding to immobilized collagen by both the enzyme-linked immunosorbent assay and surface plasmon resonance methods. GPVI-Fc(2) bound to the surface of immobilized collagen with a dissociation constant (K(D)) of 5.76 x 10(-7) m, but the binding of GPVIex was too weak to allow estimation of this parameter. Cvx did not inhibit the binding of dimeric GPVI to collagen, indicating that the binding site of GPVI to collagen was different from that to Cvx. Taken together, our data indicate that the high affinity binding site for collagen is composed from two chains of GPVI. Furthermore, they suggest that the binding sites for Cvx are different from the collagen-binding sites and do not need to be formed by two GPVI molecules. Because dimeric GPVI is the only form that shows high affinity to fibrous collagen, our results indicate that GPVI would be present as a dimeric form on the platelet. Moreover, surface plasmon resonance indicated that there is no detectable interaction between soluble collagen and GPVI, supporting our previous observation that GPVI only reacts with fibrous collagen.

Animals↗
PubMed1993

Detection of Luse bodies, spiralled collagen, dysplastic collagen, and intracellular collagen in rheumatoid connective tissues: an electron microscopic study.

BACKGROUND: Rheumatoid arthritis is a chronic inflammatory disease leading to alterations of the extracellular matrix in tendons, ligaments, and cartilage. The structural changes of the collagenous systems in rheumatoid connective tissues are largely unknown, however. METHODS: Thirty four samples of menisci, 36 cruciate ligaments, and four tendons were taken during joint surgery in patients with rheumatoid arthritis. Eighteen menisci, 35 ligaments, and 30 tendons obtained at necropsy served as a control group. The extracellular matrix in the two groups was analysed by the combined use of transmission and scanning electron microscopy, immunohistochemistry with monoclonal antibodies recognising collagen types IV and VI, and ultramorphometry. RESULTS: Normal tendons and ligaments predominantly showed a unidirectional fibril arrangement. Whereas type IV collagen showed a positive staining pattern along all basement membranes, type VI collagen formed fine, filaments aligned in parallel. In patients with rheumatoid arthritis a significant reduction of the mean diameter of the collagen fibrils was found owing to the presence of thin collagenous fibrils 20-60 nm in diameter. Most of these fibrils showed considerable changes in their arrangement with irregular courses (so-called interfibrillar dysplastic collagen). Up to 410 nm thick frayed fibrils with irregular outlines (spiralled collagen) and intracellular collagen forms were found in rheumatoid tissues. In addition, atypical thick collagenous structures with 41 nm periodicity (Luse bodies) were detected in the matrix. The upregulation of type IV collagen in rheumatoid arthritis was associated with an increase in the vascular density. The expression of type VI collagen was upregulated in fibrotic zones. CONCLUSIONS: The dramatic ultrastructural collagen changes lead to a structural and functional insufficiency of the extracellular matrix in rheumatoid connective tissues. The results suggest that collagen alterations may contribute to the development of tendon and ligament ruptures in rheumatoid arthritis.

Aged↗
PubMed1994

Conformation dependence of integrin-type II collagen binding. Inability of collagen peptides to support alpha 2 beta 1 binding, and mediation of adhesion to denatured collagen by a novel alpha 5 beta 1-fibronectin bridge.

The mechanism of interaction of chondrocytic cells with cartilage-specific type II collagen has been examined using HCS-2/8 human chondrosarcoma cells as a model system. By the criteria of specific collagen secretion and integrin expression profile, HCS-2/8 have a similar differentiated phenotype to normal chondrocytes and are therefore a good model system. HCS-2/8 cells were able to attach and spread on both native and heat-denatured pepsinised type II collagen, and assays using denatured cyanogen bromide fragments apparently localised the major cell binding site to the CB10 fragment. However, when they were used as soluble inhibitors, cyanogen bromide fragments were found to block adhesion to denatured collagen, but had no effect on either attachment or spreading on the native molecule. The inability of cyanogen bromide fragments to reproduce the cell binding site of native collagen demonstrated a strict dependence on collagen conformation. This was also reflected in the receptors that were employed by HCS-2/8 cells for binding to type II collagen: binding to native collagen was mediated by the integrin alpha 2 beta 1 while binding to denatured collagen was mediated by a novel alpha 5 beta 1-fibronectin bridge. The identification of this bridge adds to the mechanisms by which cells can bind to denatured collagens. The previously characterised KDGEA active site peptide from type I collagen was found to be inactive as an inhibitor of type II collagen-mediated adhesion. The implications of these findings for the strategies used to identify adhesive active sites within collagens are discussed. In particular, these data suggest that, unlike other integrin ligands, a synthetic peptide-based approach is not suitable for the identification of collagen active sites.

Amino Acid Sequence↗
PubMed2001

[Safety studies on collagen viscoelastic substance as an auxiliary agent in anterior segment surgery--assays of anti-collagen antibodies in blood and residual concentration of collagen in the anterior chamber of rabbits].

PURPOSE: Alkali-soluble collagen solution was assessed as a possible viscoelastic substance in anterior segment surgery, in terms of its safe applicability by assaying antigenicity, disappearance rate of collagen from the anterior chamber, and histopathological effect on the corneal tissue. METHODS: The aqueous humor of rabbits was replaced with collagen solution three times. Then, follow-up clinical examinations with hand-slitlamp-microscopy, tonometry, pachymetry, and specular microscopy as well as ophthalmic histopathological examination were performed. Remaining collagen concentration in the aqueous humor at 1, 3, 5, 8, 24 and 72 hours after injection was determined to evaluate the disappearance rate of collagen from the aqueous humor with time. In vivo effects of chemical modification of collagen and buffer concentration on the corneal tissue were further studied by using transmission electron microscope (TEM) to find an optimum condition for collagen application. RESULTS: Neither anti-collagen antibody formation, nor inflammatory responses in the anterior segment and systemic symptoms were observed even after 3 injections of collagen solution, except for 1 case which showed corneal opacity. As much as 97.4% of the collagen injected into the anterior chamber disappeared from the eyeball. On the basis of TEM findings, succinylated collagen in diluted phosphate buffer seems to be superior to alkali soluble collagen in terms of corneal tissue protection. CONCLUSION: Collagen specifically prepared for this study showed no antigenecity and disappeared promptly from the anterior chamber. The optimal form of collagen in terms of corneal protection was discussed.

Animals↗
PubMed1988

The immune response of guinea-pigs to type II collagen: poor cross-reactivity with homologous type II collagen accounts for resistance to collagen-induced arthritis.

In order to determine the susceptibility of guinea-pigs to collagen-induced arthritis (CIA), Hartley and Strain 13 guinea-pigs were immunized with heterologous or homologous type II collagen. None of the animals developed CIA. Because immunity to type II collagen plays a critical role in CIA, we characterized the guinea-pig's immune response to determine the basis for this resistance. Guinea-pigs develop cellular and humoral reactivity to heterologous type II collagen similar to that of CIA-susceptible rats. The reactions distinguish type I from type II collagen but not among several heterologous type II collagens. The cell-mediated immune (CMI) response was specific for determinants on the primary amino acid structure of collagen, whether native or denatured collagen was used for immunization; however, the humoral response was specific for the form of the molecule used for immunization. Guinea-pigs differ from CIA-susceptible rats in that immunization with homologous or heterologous type II collagen fails to induce significant cross-reactive immunity with the homologous antigen. A transient arthritis could be induced in animals immunized with heterologous type II collagen by injecting them intra-articularly with heterologous but not with homologous type II collagen. Our results show that the disparity between immunity to type II collagen and the susceptibility to develop CIA in guinea-pigs is due to their poor cross-reactive immune response to autologous type II collagen.

Animals↗
PubMed1990

A 48 kDa collagen-binding phosphoprotein isolated from bovine aortic endothelial cells interacts with the collagenous domain, but not the globular domain, of collagen type IV.

We have identified collagen-binding proteins in detergent extracts of metabolically labelled bovine aortic endothelial cells (BAEC) by collagen type IV-Sepharose affinity chromatography. The major collagen type IV-binding protein identified by SDS/PAGE had a molecular mass of 48 kDa, which we term the 'collagen-binding 48 kDa protein' (CB48). The pI of CB48 was 8.0-8.3 in a two-dimensional gel system, running non-equilibrium pH gel electrophoresis in the first dimension and SDS/PAGE in the second dimension. Under these conditions CB48 separated into two major (a and b) and one minor isoform (c); a was the most basic of the three isoforms. Two-dimensional chymotryptic peptide maps derived from each individual isoform were virtually identical. The charge differences between the isoforms were due in part to differential H3(32)PO4 incorporation by the protein. CB48 bound to intact collagen type IV and the collagenous region of collagen type IV, but not to the globular NC1 domain. Cell-surface labelling and indirect immunofluorescence experiments localized the bulk of CB48 intracellularly in the endoplasmic reticulum Golgi region, with a minor population of molecules on the cell surface. A specific rabbit polyclonal anti-CB48 serum did not inhibit the attachment or spreading of BAEC to collagen type IV in an 'in vitro' adhesion assay, suggesting that the cell-surface population of CB48 is not involved in BAEC adhesion. We conclude that CB48 is a collagen-binding phosphoprotein that interacts with the collagenous domain of collagen type IV and may be involved in intracellular transport of collagen molecules.

Animals↗
PubMed1996

The evolution of fibrillar collagens: a sea-pen collagen shares common features with vertebrate type V collagen.

The extracellular matrix of marine primitive invertebrates (sponges, polyps and jellyfishes) contains collagen fibrils with narrow diameters. From various data, it has been hypothesized that these primitive collagens could represent ancestral forms of the vertebrate minor collagens, i.e., types V or XI. Recently we have isolated a primitive collagen from the soft tissues of the sea-pen Veretillum cynomorium. This report examines whether the sea-pen collagen shares some features with vertebrate type V collagen. Rotary shadowed images of acid-soluble collagen molecules extracted from beta-APN treated animals, positive staining of segment-long-spacing crystallites precipitated from pepsinized collagen, Western blots of the pepsinized alpha1 and alpha2 chains with antibodies to vertebrate types I, III and V collagens, and in situ gold immunolabeling of ECM collagen fibrils were examined. Our results showed that the tissue form of the sea-pen collagen is a 340-nm threadlike molecule, which is close to the vertebrate type V collagen with its voluminous terminal globular domain, the distribution of most of its polar amino-acid residues, and its antigenic properties.

Amino Acid Sequence↗
PubMed1991

Copolymerization of pNcollagen III and collagen I. pNcollagen III decreases the rate of incorporation of collagen I into fibrils, the amount of collagen I incorporated, and the diameter of the fibrils formed.

Previous observations suggested that pNcollagen III, the partially processed form of type III procollagen, coats fibrils of collagen I and thereby helps regulate the diameter of fibrils formed by collagen I. The previous observations, however, did not exclude the possibility that pNcollagen III was deposited on preformed collagen I fibrils after the fibrils were assembled. Here, mixtures of pNcollagen III and collagen I were generated simultaneously by enzymatic cleavage of precursor forms of the proteins. The results demonstrated that pNcollagen III forms true copolymers with collagen I. The presence of pNcollagen III both inhibited the rate at which collagen I assembled into fibrils and decreased the amount of collagen I incorporated into fibrils at steady-state equilibrium. In addition, the results demonstrated that copolymerization of pNcollagen III with collagen I generated fibrils that were thinner than fibrils generated under the same conditions from collagen I alone. Increasing the initial molar ratio of pNcollagen III to collagen I in the solution-phase increased the amount of pNcollagen III copolymerizing with collagen I and progressively decreased the diameter of the fibrils. Therefore, the copolymers were heterogeneous in that the stoichiometry of the two monomers in the fibrils varied. The results are consistent with a model in which pNcollagen III can regulate the diameter of collagen I fibrils by coating the surface of the fibrils and thereby allow tip growth but not lateral growth of the fibrils.

Collagen↗
PubMed1984

Localization of type V collagen and type IV collagen in human cornea, lung, and skin. Immunohistochemical evidence by anti-collagen antibodies characterized by immunoelectroblotting.

Tissue distribution of Type V collagen in comparison with Type IV collagen was investigated by indirect immunofluorescence microscopy. Affinity-purified rat antibodies to Type IV and Type V collagens obtained from human placenta reacted specifically only with the corresponding type of collagen in both native and denatured conformations. In indirect immunofluorescent stainings of human skin, lung, and cornea tissues, Type IV and Type V collagens showed distinct distributions. Type IV collagen was distributed exclusively in basement membrane. However, Type V collagen had two characteristic features; a diffuse distribution in interstitium and the locations on or adjacent to basement membrane. On the basis of these findings and of biochemical characterization of the collagens, it is postulated that Type V collagen is an intermediate collagen, possibly having a function of binding or connecting of interstitial collagen fibrils with membranous collagen networks.

Adult↗
PubMed2001

alpha 1(Xx) collagen, a new member of the collagen subfamily, fibril-associated collagens with interrupted triple helices.

Chick cDNA clones for a new member of the FACIT (fibril-associated collagens with interrupted triple helices) subfamily have been isolated and sequenced. The collagen chain encoded by these cDNAs was assigned the next consecutive number, making it the alpha1(XX) collagen chain. Assignment of type XX collagen to the FACIT family was based on sequence similarities to types XII and XIV collagen. Type XX collagen mRNA is not abundant in the chick embryo. It is most prevalent in corneal epithelium. It is also detectable by reverse transcription polymerase chain reaction in embryonic skin, sternal cartilage, and tendon, but is barely detectable in calvaria, notochord, or neural retina at select stages of development, suggesting that it is not expressed in these tissues. The cDNA predicts that the alpha1(XX) collagen polypeptide is smaller than the short forms of collagen XII and XIV. A polyclonal antibody against a synthetic alpha1(XX) peptide reacts with polypeptide bands of 185, 170, and 135 kDa by Western blot analysis. From its similarity to types XII and XIV collagen, type XX is expected to bind to collagen fibrils, projecting the amino-terminal domains away from the fibrillar surface. The projecting NC 3 domains are predicted to be about half the length of those of collagen XIV.

Amino Acid Sequence↗