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J Schaller

Publications and source records attributed to J Schaller.

At least 19 recordsLinked to original sources
PubMed2006

[Dermatohistology laboratory].

Dermatohistology plays an essential role in the diagnosis of cutaneous tumors and inflammatory skin diseases. In order to practice dermatohistology properly, one needs not only a well-equipped laboratory but also properly trained dermatohistologists and laboratory technicians. We discuss the establishment of a dermatohistology laboratory. The technical procedures involved in making slides, ranging from traditional H & E stains, through special stains, immunohistochemistry and molecular-biological techniques, are viewed. The importance of clinical-histologic correlation and the limitations of pure histologic diagnostics are demonstrated with illustrative cases.

Dermatology↗
PubMed2005

Palmar atypical lipomatous tumour with spindle cell features (well-differentiated spindle cell liposarcoma): a rare neoplasm arising in an unusual anatomical location.

Lipomatous tumours, both benign and malignant, arising on the hands are uncommon. We present a rare atypical lipomatous tumour with spindle cell features (synonym: well-differentiated spindle cell liposarcoma) arising on the left palm of a 54-year-old male patient. The neoplasm presented as a long-standing, exophytic neoplasm measuring 9 x 9 cm. The well-circumscribed neoplasm was completely excised, and margins were tumour free. Histologically, the neoplasm showed features closely resembling spindle cell lipoma, being composed of mature adipocytic cells associated with bland, neuroid spindle cells staining positively for CD34. However, focally, atypia of adipocytic and stromal cells as well as scattered lipoblasts were noted, and immunohistochemical stainings showed focal overexpression of MDM 2 and CDK4. Aypical lipomatous tumour with spindle cell features may arise very rarely in palmar location and has to be distinguished from a number of benign and malignant mesenchymal neoplasms.

Diagnosis, Differential↗
PubMed2002

Prospective evaluation of the peptide-bound collagen type I cross-links N-telopeptide and C-telopeptide in predicting bone metastases status.

PURPOSE: The objective assessment of bone metastases is currently based on serial changes in skeletal survey. We performed a prospective study to determine whether a correlation exists between the biochemical markers of bone turnover and x-ray evaluation of bone metastases in patients with or without bisphosphonate therapy, and whether bone markers are influenced by extraskeletal disease. PATIENTS AND METHODS: Patients with either bone or extraskeletal metastases were consecutively enrolled and World Health Organization response criteria were applied for both bone and extraosseous disease every 3 to 4 months. Serum levels of bone-specific alkaline phosphatase (B-AP) and C-telopeptide (ICTP) and urine levels of N-telopeptide (NTX) were measured monthly. The data were analyzed by generalized estimation equation regression. RESULTS: We studied 97 patients with bone metastases (52 also with extraskeletal metastases) and 26 with extraosseous disease only. Median time on study was 153 days, and 281 objective evaluations (171 in bone) were performed. With bisphosphonates (49 patients receiving pamidronate and three receiving clodronate), percent change from levels without therapy was 47% for NTX (P <.001) and 69% for B-AP (P =.008). With disease progression in bone, percent change from mean levels during stable disease was 152% for NTX (P <.001) and 144% for ICTP (P <.001) regardless of bisphosphonate therapy. NTX had the highest positive predictive value (71%) for the diagnosis of bone metastases progression. Extraskeletal disease had no significant effect on bone markers. CONCLUSION: Urinary NTX may be a valuable bone marker to assess the antiresorptive effect of bisphosphonate therapy and to evaluate the progression of bone metastases.

Adult↗
PubMed2001

Plant adenosine 5'-phosphosulfate reductase is a novel iron-sulfur protein.

Adenosine 5'-phosphosulfate reductase (APR) catalyzes the two-electron reduction of adenosine 5'-phosphosulfate to sulfite and AMP, which represents the key step of sulfate assimilation in higher plants. Recombinant APRs from both Lemna minor and Arabidopsis thaliana were overexpressed in Escherichia coli and isolated as yellow-brown proteins. UV-visible spectra of these recombinant proteins indicated the presence of iron-sulfur centers, whereas flavin was absent. This result was confirmed by quantitative analysis of iron and acid-labile sulfide, suggesting a [4Fe-4S] cluster as the cofactor. EPR spectroscopy of freshly purified enzyme showed, however, only a minor signal at g = 2.01. Therefore, Mössbauer spectra of (57)Fe-enriched APR were obtained at 4.2 K in magnetic fields of up to 7 tesla, which were assigned to a diamagnetic [4Fe-4S](2+) cluster. This cluster was unusual because only three of the iron sites exhibited the same Mössbauer parameters. The fourth iron site gave, because of the bistability of the fit, a significantly smaller isomer shift or larger quadrupole splitting than the other three sites. Thus, plant assimilatory APR represents a novel type of adenosine 5'-phosphosulfate reductase with a [4Fe-4S] center as the sole cofactor, which is clearly different from the dissimilatory adenosine 5'-phosphosulfate reductases found in sulfate reducing bacteria.

Amino Acid Sequence↗
PubMed2000

Adenosine 5'-phosphosulfate sulfotransferase and adenosine 5'-phosphosulfate reductase are identical enzymes.

Adenosine 5'-phosphosulfate (APS) sulfotransferase and APS reductase have been described as key enzymes of assimilatory sulfate reduction of plants catalyzing the reduction of APS to bound and free sulfite, respectively. APS sulfotransferase was purified to homogeneity from Lemna minor and compared with APS reductase previously obtained by functional complementation of a mutant strain of Escherichia coli with an Arabidopsis thaliana cDNA library. APS sulfotransferase was a homodimer with a monomer M(r) of 43,000. Its amino acid sequence was 73% identical with APS reductase. APS sulfotransferase purified from Lemna as well as the recombinant enzyme were yellow proteins, indicating the presence of a cofactor. Like recombinant APS reductase, recombinant APS sulfotransferase used APS (K(m) = 6.5 microM) and not adenosine 3'-phosphate 5'-phosphosulfate as sulfonyl donor. The V(max) of recombinant Lemna APS sulfotransferase (40 micromol min(-1) mg protein(-1)) was about 10 times higher than the previously published V(max) of APS reductase. The product of APS sulfotransferase from APS and GSH was almost exclusively SO(3)(2-). Bound sulfite in the form of S-sulfoglutathione was only appreciably formed when oxidized glutathione was added to the incubation mixture. Because SO(3)(2-) was the first reaction product of APS sulfotransferase, this enzyme should be renamed APS reductase.

Amino Acid Sequence↗
PubMed2000

A lysine rich C-terminal tail is directly involved in the toxicity of CSTX-1, a neurotoxic peptide from the venom of the spider Cupiennius salei.

CSTX-1 (74 amino acids, 8,352.62 Da) is a potent neurotoxin from the venom of Cupiennius salei. With the monoclonal antibody 9H3 against CSTX-1, we identified two similar peptides by Western blot analysis. These two peptides were purified by RP-HPLC: CSTX-2a (61 amino acids, 6865.75 Da) and CSTX-2b (60 amino acids, 6709.57 Da). Using ESI-MS analysis and sequencing we verified that CSTX-2a is a truncated version of CSTX-1. CSTX-2b differs from CSTX-2a by the absence of Arg61. Toxicity of CSTX-1, CSTX-2a, and CSTX-2b to Drosophila melanogaster showed that the absence of the last 13 amino acids of CSTX-1 results in a seven-fold activity loss. CSTX-2b, which lacks Arg61 is 190-fold less toxic. We conclude that the C-terminal part of CSTX-1, especially Arg61, is essential for the expression of toxicity. CSTX-1 is degraded to CSTX-2a and CSTX-2b by proteases that are released from venom gland cells by apocrine secretion.

Amino Acid Sequence↗
PubMed2000

Characterisation of antibacterial activity of peptides isolated from the venom of the spider Cupiennius salei (Araneae: Ctenidae).

The characterisation of the antimicrobial activity of five antibacterial peptides, isolated from the venom of the neotropical wandering spider Cupiennius salei is reported here. The peptides have a molecular mass, determined by electrospray ionisation-mass spectrometry, between 3-4 kDa. Minimal inhibitory concentrations against five different bacteria species were determined by a liquid growth inhibition assay. All five peptides showed minimal inhibitory concentrations that are comparable to those of other known antibacterial peptides, like insect defensins and cecropins, found in the last years in a large diversity of animals. The peptides are supposed to lyse the cells by formation of either distinct channels or pores, but their mode of action is not yet revealed.

Anti-Bacterial Agents↗
PubMed2000

Hidden effects of cryopreservation on quality of human spermatozoa.

The effects of cryopreservation on two characteristics of human spermatozoa were investigated: the early phases of disturbed plasma membrane function and the activity of enzymes in intact spermatozoa. The membrane function was detected by means of the calcium-dependent binding of fluorescein isothiocyanate (FITC)-conjugated Annexin V to sperm plasma membranes. Annexin V monitors the translocation of phosphatidylserine from the inner to the outer leaflet of the plasma membrane, which is one of the earliest features of membrane disintegration. For the second aim synthetic fluorogenic substrates for peptidases, proteinases, esterases, elastases and collagenases were applied. These substrates, CellProbe trade mark reagents consist of different peptide sequences, specific for the enzymes, and a fluorescein- or rhodamine 110-dye moiety. They enter the cells without previous membrane permeabilisation and exhibit fluorescence after cleavage depending on enzyme activity. The number of positive cells and the intensity of the fluorescence were determined by flow cytometric analysis comparing fresh spermatozoa with cryopreserved ones. Thirty-five semen samples collected from 35 donors were cryopreserved using the freezing medium TEST yolk buffer. All specimens showed normal spermiogram parameters. Twenty-five of the samples were used for detection of Annexin V-FITC binding and 10 semen samples for investigations of the intracellular enzymes. The Annexin V-assay applied two fluorescent dyes (Annexin V, AN and propidium iodide, PI) which led to three groups of spermatozoa (a) viable spermatozoa (AN V-negative and PI-negative), (b) dead spermatozoa (AN V-positive and PI-positive) and (c) cells with impaired but integer plasma membrane (AN V-positive and PI-negative). The percentage of vital Annexin V-negative spermatozoa (x +/- SEM) decreased significantly (p < 0.001) from fresh spermatozoa (51.6 +/- 3.1) to cryopreserved spermatozoa (26.6 +/- 2.2%) and was associated with their motility (57.9 +/- 1.9% motile fresh spermatozoa vs. 22.6 +/- 3.9% motile sperm after cryopreservation). Of the spermatozoa 28.2% were Annexin V-positive before and 44.4% after cryostorage even though they did not bind to PI. Thus, vital spermatozoa showed a disturbed membrane function indicating viability before as well as after cryostorage. Moreover, after cryopreservation the spermatozoal fluorescence increased applying substrates for butyryl esterase (p < 0.05), prolyl-aminopeptidase (p < 0.001) and val-lys-(VK)-cathepsin (p < 0.001). In contrast, the activities of fluorescein diacetate (FDA)- and FDA/sodium fluoride (NAF)-esterase (p < 0.05), ala-ala-pro-val-(AAPV)-elastase (p < 0.001), gly-pro-leu-gly-pro-(GPLGP)-collagenase (p < 0.05) and gly-gly-leu-(GGL)-subtilisin (p < 0.001) decreased after cryopreservation. The substrates for arg-gly-glut-ser-(RGES)-elastase, gly-phenyl-gly-ala-(GFGA)-collagenase and threo-pro-(TP)-cathepsin were not cleaved before as well as after cryostorage. In addition to the known effects of sperm cryopreservation our results showed two further alterations of human ejaculated spermatozoa: (a) disturbed plasma membrane function, which is not detectable by supravital staining and (b) a changed pattern of intracellular enzyme activities.

Journal Article↗
PubMed2000

Flow cytometric analysis of enzymes in live spermatozoa before and after cryostorage.

Synthetic fluorogenic substrates, like the CellProbe reagents, can determine enzymes in vital human spermatozoa. These substrates will enter the cells without previous cell permeabilization and exhibit fluorescence after cleavage depending on enzyme activity. They consist of different peptide sequences, specific for the enzymes, and a fluorescein- or rhodamine 110-dye moiety. The number of positive cells and the intensity of the fluorescence can be determined by flow cytometric analysis. We investigated several enzymes (peptidases, proteinases, esterases, elastases and collagenases) in intact spermatozoa before and after cryoprotection. Semen samples with normal spermiogram parameters were cryoprotected using the freezing medium TEST yolk buffer (TYB). Fresh spermatozoa showed a marked fluorescence after incubation with the synthetic substrates for the aminopeptidase M, butyryl esterase, fluorescein diacetate (FDA)-and FDA/sodium fluoride (NAF)-esterase, ala-ala-pro-val (AAPV)-elastase, gly pro-leu-gly pro-(GPLGP)-collagenase, gly gly leu-(GGL)-subtilisin as well as lys-ala-(LA)-dipeptidyl peptidase (DPP) II. After cryopreservation the spermatozoal fluorescence increased applying substrates for butyryl esterase (P<0.05), prolyl-aminopeptidase (P<0.001) and val-lys-(VK)-cathepsin (P<0.001) most probably due to elevated enzyme activities. The activities of FDA-esterase (P<0.05) and FDA/NAF-esterase (P<0.05), AAPV-elastase (P<0.01), GPLGP-collagenase (P<0.05) and GGL-subtilisin (P<0.001) decreased after cryopreservation. The substrates for arg-gly glut-ser-(RGES)-elastase, gly phenyl-gly ala-(GFGA)-collagenase and threo-pro-(TP)-cathepsin were not cleaved before as well as after cryostorage. The substrates for subtilisin an

Cryopreservation↗
PubMed2000

Local application of capsaicin into the draining lymph nodes attenuates expression of adjuvant-induced arthritis.

Adjuvant-induced experimental arthritis (AA) was examined in adult male Lewis rats after isolated capsaicin (CAPS)-induced loss of small, nonmyelinated, afferent fibers in lymph nodes draining the site of adjuvant challenge. AA was induced by intradermal injection of Freund's complete adjuvant (CFA) into the subplantar area of the right hind paw. Controls received similar injections of mineral oil, the vehicle for CFA. One day later, half of the CFA-treated rats and half of the mineral oil-treated rats received injections of CAPS bilaterally into the draining lymph nodes (DLN). The DLN of remaining rats were injected with 50:50 ethanol/sterile physiological saline, the vehicle for CAPS. This paradigm resulted in four groups designated: CFA/CAPS, CFA/vehicle, vehicle/CAPS and vehicle/vehicle. Since substance P (SP) is present in small, nonmyelinated, afferent fibers, the target of the neurotoxin, CAPS, a radioimmunoassay specific for SP was used to verify the loss of these nerve fibers. CAPS injections into the DLN resulted in a loss in SP concentration in the DLN, with no depletion of SP in the spleen or sciatic nerve. These findings support the destruction of SP-containing nerves, which we interpret as verification of the selective loss of small, non-myelinated afferent nerves in the DLN with no significant spread of the neurotoxin to the nearby sciatic nerves which supply small, nonmyelinated, afferent fibers to the hind limb joints. Also, preservation of SP content in spleen indicates CAPS did not circulate via the lymphatic drainage. No chronic inflammation was observed in the fore or hind limbs from rats treated with the vehicle for CFA (vehicle/vehicle, vehicle/CAPS) at any time during the study. In CFA/vehicle-treated rats, bilateral, symmetrical inflammation of the hind limbs was apparent 14 days after challenge with CFA, and became progressively more inflamed through day 20. In contrast, hind limb inflammation in arthritic rats treated with CAPS was not symmetrical. On days 14 and 20 after challenge with CFA, the inflammatory response in the left hind limb, contralateral to the site of CFA injection, was significantly (p < 0.05) attenuated compared with the response seen on the right side of CFA/CAPS-treated rats, and with the response seen in left hind limb of CFA/vehicle-treated animals. In fact, the mean dorsoplantar width of contralateral hind limbs from CFA/CAPS-treated animals was not different from that measured in non-AA control groups. These findings support a role for small, nonmyelinated, sensory nerves that modulate immune responses in DLN in the development and progression of AA in Lewis rats.

Afferent Pathways↗
PubMed1999

Annexin VI participates in the formation of a reversible, membrane-cytoskeleton complex in smooth muscle cells.

The plasmalemma of smooth muscle cells is periodically banded. This arrangement ensures efficient transmission of contractile activity, via the firm, actin-anchoring regions, while the more elastic caveolae-containing "hinge" regions facilitate rapid cellular adaptation to changes in cell length. Since cellular mechanics are undoubtedly regulated by components of the membrane and cytoskeleton, we have investigated the potential role played by annexins (a family of phospholipid- and actin-binding, Ca(2+)-regulated proteins) in regulating sarcolemmal organization. Stimulation of smooth muscle cells elicited a relocation of annexin VI from the cytoplasm to the plasmalemma. In smooth, but not in striated muscle extracts, annexins II and VI coprecipitated with actomyosin and the caveolar fraction of the sarcolemma at elevated Ca(2+) concentrations. Recombination of actomyosin, annexins, and caveolar lipids in the presence of Ca(2+) led to formation of a structured precipitate. Participation of all 3 components was required, indicating that a Ca(2+)-dependent, cytoskeleton-membrane complex had been generated. This association, which occurred at physiological Ca(2+) concentrations, corroborates our biochemical fractionation and immunohistochemical findings and suggests that annexins play a role in regulating sarcolemmal organization during smooth muscle contraction.

Actomyosin↗
PubMed1999

Solution structure and dynamics of the plasminogen kringle 2-AMCHA complex: 3(1)-helix in homologous domains.

The kringle 2 (K2) module of human plasminogen (Pgn) binds L-lysine and analogous zwitterionic compounds, such as the antifibronolytic agent trans-(aminomethyl)cyclohexanecarboxylic acid (AMCHA). Far-UV CD and NMR spectra reveal little conformational change in K2 upon ligand binding. However, retarded (1)H-(2)H isotope exchange kinetics induced by AMCHA indicate stabilization of the K2 conformation by the ligand. Assessment of secondary structure content from CD spectra yields approximately 26% beta-STRAND, approximately 13% beta-TURN, approximately 15% 3(1)-HELIX, and approximately 6% 3(10)-HELIX. The NMR solution conformation of the K2 domain complexed to AMCHA has been determined [heavy atom rmsd = 0.49 +/- 0.09A (BACKBONE) AND 1.02+/- 0.08 (ALL)]. The K2 molecule has overall dimensions of approximately 34.5A times approximately 33.4A times approximately 22.7A . Analogous with the polypeptide outline of homologous domains, K2 contains three short antiparallel beta-sheets (paired strands 15-16/20-21, 24-25/48-49, and 62-64/72-74) and four defined beta-turns (residues 6-9, 16-19, 53-56, AND 67-70). Consistent with the CD analysis, albeit novel in the context of kringle folding, the NMR structure reveals an unpaired beta-strand structured by residues 30-32, a turn of 3(10)-helix compromising residues 38-41, and a 3(1)-helix for residues 21-24 and 74-79. We also identify alignable 3(1)-helices in previously reported homologous kringle structures. Rather high order parameter S(2) values ( = approximately 0.85 +/- 0.04) characterize the K2 backbone dynamics. The lowest flexibility is observed for the two inner loop segments of residues 51-63 AND 63-75 ( = approximately 0.86-0.87 +/- 0.03). Overhauser connectivities reveal close hydrophobic contacts of the ligand ring with side chains of Tyr(36), Trp(62), Phe(64), Trp(72), AND Leu(74). In most K2 structures, the N atom of AMCHA places itself approximately 3.9 and 4.4A from the anionic groups of Glu(57) and Asp(55), respectively, while its carboxylate group, H-bonded to the Tyr(36) side chain OH(eta), ion-pairs the Arg(71) guanidinium group. Consistent with the preference of K2 for binding 5-aminopentanoic acid over 6-aminohexanoic acid, the positions of the ionic centers within the K2 binding site approach each other approximately 1A closer relative to what is observed in lysine binding sites of homologous Pgn modules.

Amino Acid Motifs↗
PubMed1999

Dual role for noradrenergic innervation of lymphoid tissue and arthritic joints in adjuvant-induced arthritis.

The role of noradrenergic innervation in the disease outcome of adjuvant-induced arthritis (AA) has been examined following (1) systemic administration of guanethidine and (2) local application of 6-hydroxydopamine (6-OHDA) into the lymph nodes that drain the hind limbs (DLN). Sympathetic denervation by these different neurotoxins produced directionally opposite effects on disease outcome. These conflicting findings could be explained from differential denervation of sympathetic nerves in key target tissues that result from different routes of neurotoxin administration. Alternatively, these conflicting data could be due to differences in the mechanisms by which guanethidine and 6-OHDA destroy sympathetic nerve terminals. In this study, we compared disease outcome in AA following systemic and local DLN application of 6-OHDA to determine whether the route of administration is important to the development and progression of AA. Bilateral local DLN application of 6-OHDA or vehicle was performed 1 day before injection of Freund's complete adjuvant (CFA) to induce arthritis. For systemic denervation, 6-OHDA or vehicle was given by ip injections on days 1, 3, and 5 prior to CFA challenge and then once a week. Local DLN application of 6-OHDA resulted in significant increases in dorsoplantar width in arthritic rats by 27 days following CFA treatment compared to those of non-denervated arthritic rats. In contrast, systemic denervation in arthritic rats significantly decreased dorsoplantar widths 27 days after CFA treatment compared to those in sympathetically intact arthritic animals. X-ray analysis confirmed these findings. Further, local DLN application of 6-OHDA exacerbated the disease regardless of whether the neurotoxin was administered prior to immunization with CFA or closer to the time of disease onset. Our findings indicate that the route of 6-OHDA administration for denervation of sympathetic innervation is an important parameter in determining disease outcome, presumably due to differential sympathetic denervation of target tissues that are involved in disease development and progression. 6-OHDA administration into local DLN denervated these lymph nodes, but spared sympathetic innervation of the hind limbs, a pattern of sympathetic denervation that resulted in disease exacerbation. In contrast, systemic 6-OHDA administration which denervated both the arthritic joints and the secondary lymphoid organs attenuated the severity of AA. This study supports a dual role for NA innervation in modulating the severity of AA by innervation of the arthritic joints and lymphoid organs.

Animals↗
PubMed1999

Expression, isolation and characterization of a mutated human plasminogen kringle 3 with a functional lysine binding site.

Each kringle of human plasminogen (HPg) except kringle 3 (K3) exhibits affinity for omega-aminocarboxylic acids. Assuming that the K3 domain contains a preformed but nonfunctional lysine binding site (LBS), Lys311 was altered by site-directed mutagenesis into Asp311 in accordance with the consensus sequence of the LBS. Cys297 involved in the interkringle disulfide bridge was mutated into Ser297 to minimize dimerization and aggregation. The mutated K3 TYQ[K3HPg/C297S/K311D]DS (r-K3mut) was expressed in Escherichia coli, isolated on an Ni2(+)-nitrilotriacetic acid-agarose column, refolded and purified on a lysine Bio-Gel column. Fluorescence titration indicates affinity of r-K3mut for omega-aminocarboxylic acids with the following association constants (Kass, mM-1): 5-aminopentanoic acid: 1.3; 6-aminohexanoic acid: 4.2; 7-aminoheptanoic acid: 0.5; trans-(aminomethyl)cyclohexanecarboxylic acid: 12.7; p-benzylaminesulfonic acid: 11.8. r-K3mut exhibits an affinity similar to native and mutated (R220G, E221D) K2. The results indicate the presence of a preformed but nonfunctional LBS in native K3 of HPg. We were able to demonstrate for the first time that an appropriate mutation in the LBS of a kringle produced a weak but distinct affinity for omega-aminocarboxylic acids.

Amino Acid Sequence↗
PubMed1999

Detection of human papillomavirus type 10 DNA in eccrine syringofibroadenomatosis occurring in Clouston's syndrome.

Syringofibroadenomatosis is often associated with an underlying condition such as diabetes mellitus or hidrotic ectodermal dysplasia. By reason of these associations, a reactive or hamartomatous cause is suspected. We report a case of a 71-year-old woman with Clouston's syndrome in whom progressive multiple palmoplantar syringofibroadenomas developed over a 10-year period. The syringofibroadenomas formed flat-topped papules simulating verruca plana; the widespread distribution and chronic progressive course resembled epidermodysplasia verruciformis. Contiguous with the syringofibroadenoma's characteristic epithelial-stromal proliferation were epidermal changes of verruca plana. Evidence of human papillomavirus (HPV) infection was verified by immunolabeling with antibodies to bovine papillomavirus type 1 and detection of HPV 10 viral DNA by means of polymerase chain reaction. Rather than a hamartomatous process, these findings suggest that syringofibroadenomas occurring in the setting of Clouston's syndrome could represent an HPV-induced epithelial proliferation.

Aged↗
PubMed1999

Homologous plasminogen N-terminal and plasminogen-related gene A and B peptides. Characterization of cDNAs and recombinant fusion proteins.

The cDNA corresponding to exons 2-4 of the processed human plasminogen (Pgn) gene, encoding the N-terminal peptide domain (NTP), has been cloned, expressed in Escherichia coli as a recombinant protein (r-NTP) containing a hexahistidine tag, and refolded to the native structure that contains two internal cystine bridges. RNA expression of the two Pgn-related genes, PRG A and PRG B, that potentially encode 9-kDa polypeptides having extensive similarity to the NTP has been investigated. Using RNA-based PCR with liver RNA as template, we demonstrate that PRG A encodes a detectable mRNA species. PRG A and PRG B have been found to be transcribed in the liver and yield virtually identical mRNAs. Neither of the PRGs are expressed in a variety of other normal tissues, as determined by Northern blot analysis. Factor-Xa digestion of the tagged r-NTP yields cleavage products which indicates that the expressed r-NTP domain of Pgn is endowed with a flexible conformation. Recombinant PRG B protein (r-PRG B) fused to a hexahistidine tag was purified and analyzed for structural integrity. Preliminary 1H-NMR spectroscopic data for r-NTP and r-PRG B indicate relatively fast amide 1H-2H exchange in 2H2O and close conformational characteristics for the two homologous polypeptides. Far ultraviolet-CD spectra for r-NTP and r-PRG B at pH 7.0 indicate similar defined secondary structure content for both domains, with 13-17% alpha-helix and 24-27% antiparallel beta-sheet. The fact that two transcriptionally active genes encode almost identical polypeptides supports the hypothesis that the Pgn NTP, together with the putative polypeptides encoded by the PRGs, may serve an important function, such as controlling the conformation of Pgn and thus its susceptibility to tissue activators.

Amino Acid Sequence↗