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At least 19 recordsLinked to original sources
PubMed2001

Evolution of transglutaminase genes: identification of a transglutaminase gene cluster on human chromosome 15q15. Structure of the gene encoding transglutaminase X and a novel gene family member, transglutaminase Z.

We isolated and characterized the gene encoding human transglutaminase (TG)(X) (TGM5) and mapped it to the 15q15.2 region of chromosome 15 by fluorescence in situ hybridization. The gene consists of 13 exons separated by 12 introns and spans about 35 kilobases. Further sequence analysis and mapping showed that this locus contained three transglutaminase genes arranged in tandem: EPB42 (band 4.2 protein), TGM5, and a novel gene (TGM7). A full-length cDNA for the novel transglutaminase (TG(Z)) was obtained by anchored polymerase chain reaction. The deduced amino acid sequence encoded a protein with 710 amino acids and a molecular mass of 80 kDa. Northern blotting showed that the three genes are differentially expressed in human tissues. Band 4.2 protein expression was associated with hematopoiesis, whereas TG(X) and TG(Z) showed widespread expression in different tissues. Interestingly, the chromosomal segment containing the human TGM5, TGM7, and EPB42 genes and the segment containing the genes encoding TG(C),TG(E), and another novel gene (TGM6) on chromosome 20q11 are in mouse all found on distal chromosome 2 as determined by radiation hybrid mapping. This finding suggests that in evolution these six genes arose from local duplication of a single gene and subsequent redistribution to two distinct chromosomes in the human genome.

5' Untranslated Regions↗
PubMed2000

GTP, an inhibitor of transglutaminases, is hydrolyzed by tissue-type transglutaminase (TGase 2) but not by epidermal-type transglutaminase (TGase 3).

Epidermal-type transglutaminase (TGase 3) is devoid of GTPase activity, but its TGase activity is inhibited by GTP as in the case of tissue-type TGase (TGase 2). In addition, the inhibition was not affected by the presence of higher concentrations of Ca ion. These results indicate that GTP interacts with TGase 3 in a manner different from its action on TGase 2.

Animals↗
PubMedDate not supplied

Lysine-rich histone (H1) is a lysyl substrate of tissue transglutaminase: possible involvement of transglutaminase in the formation of nuclear aggregates in (CAG)(n)/Q(n) expansion diseases.

Histone H1, which contains about 27% lysine, is an excellent lysyl donor substrate of Ca(2+)-activated guinea pig liver tissue transglutaminase as judged by rapid fluorescence enhancement in the presence of the glutaminyl-donor substrate 1-N-(carbobenzoxy-L-glutaminylglycyl)-5-N-(5'N'N'-dimethylamino naphth alenesulfonyl) diamidopentane. Sodium dodecyl sulfate gel electrophoresis of a 30-min reaction mixture revealed the presence of fluorescent high-M(r) aggregates, which are also formed when histone H1 is incubated solely with activated tissue transglutaminase. Aggregate formation is even more pronounced when histone H1 is incubated with activated tissue transglutaminase and dimethylcasein (glutaminyl donor only). The findings suggest not only that histone H1 is an especially good lysyl substrate of tissue transglutaminase, but that it is also a glutaminyl substrate. Histone H1 is a good lysyl substrate of transglutaminase purified from Streptoverticillium mobaraense, suggesting that the ability of histone H1 to act as a transglutaminase lysyl substrate is widespread. In agreement with previous studies, it was found that human beta-endorphin is a moderately good substrate of tissue transglutaminase. At least 8 neurodegenerative diseases, including Huntington's disease, are caused by (CAG)(n) expansions in the genome and by an expansion of the corresponding polyglutamine domain within the expressed, mutated protein. Polyglutamine domains are excellent substrates of liver and brain transglutaminases. A hallmark of many of the (CAG)(n)/polyglutamine expansion diseases is the presence of polyglutamine-containing aggregates within the cytosol and nuclei of affected neurons. Transglutaminase activity occurs in both of these compartments in human brain. In future studies, it will be important to determine whether transglutaminases play a role in (1) cross-linking of histone H1 to glutaminyl donors (including polyglutamine domains) in nuclear chromatin, (2) the formation of nuclear aggregates in (CAG)(n)/polyglutamine expansion diseases, (3) DNA laddering and cell death in neurodegenerative diseases and (4) depletion of neuropeptides in vulnerable regions of Huntington's disease brain.

Animals↗
PubMed1991

Tissue (type II) transglutaminase covalently incorporates itself, fibrinogen, or fibronectin into high molecular weight complexes on the extracellular surface of isolated hepatocytes. Use of 2-[(2-oxopropyl)thio] imidazolium derivatives as cellular transglutaminase inactivators.

Rabbit hepatocyte surface-expressed tissue (type II) transglutaminase is shown to act as a binding site for fibrinogen or fibronectin and to covalently incorporate these glycoproteins, in addition to itself, into extracellular high molecular weight complexes. This concept is supported by the observation that a nonpeptidyl, active site-directed transglutaminase inactivator (L683685) elicited concentration-dependent (0.1-10 microM) decreases in the calcium-dependent binding and covalent cross-linking of 125I-fibrinogen, 125I-fibronectin, or [14C]putrescine by hepatocyte suspensions. In corroboration with these findings, an antiserum against rabbit liver transglutaminase, which did not cross-react with rabbit factor XIII, elicited concentration-dependent decreases in the calcium-dependent binding and covalent cross-linking of 125I-fibrinogen or [14C]putrescine by hepatocyte suspensions. Western blots of sodium dodecyl sulfate/Triton-insoluble hepatocyte fractions conducted with this antiserum, with a polyclonal antiserum against human erythrocyte transglutaminase, or with a monoclonal antibody (CUB-7401) against guinea pig liver transglutaminase detected the 80-kDa tissue transglutaminase, as well as tissue transglutaminase-immunoreactive bands of higher molecular mass (range of 90 to greater than 200 kDa). The higher molecular weight species were preferentially incorporated, in a time- and calcium-dependent manner, into very high molecular weight complexes which did not enter the stacking gel. Incorporation of these tissue transglutaminase-containing bands into the high molecular weight complexes was inhibited by L683685, indicating that cross-linking by the enzyme was responsible for the assembly of the complexes of which tissue transglutaminase was itself a component. Cellular integrins did not mediate ligand binding under the experimental conditions, as evidenced by the failure of the Arg-Gly-Asp-Ser tetrapeptide or anti-integrin antibodies to inhibit binding or cross-linking of 125I-fibrinogen or 125I-fibronectin, in the presence or absence of transglutaminase inactivators.

Animals↗
PubMed1988

The binding sites on fibrin(ogen) for guinea pig liver transglutaminase are similar to those of blood coagulation factor XIII. Characterization of the binding of liver transglutaminase to fibrin.

The present study represents detailed investigations into the nature of interactions between an intracellular "tissue" transglutaminase and a plasma protein, fibrinogen. We demonstrate a specific, saturable, and reversible binding of transglutaminase to fibrin(ogen). The binding was time- and temperature-dependent, was independent of divalent metal ions, did not require the release of either fibrinopeptide A or B, and was partially inhibited by the presence of sodium chloride or plasma proteins, properties similar to Factor XIII binding to fibrin(ogen). Both Factor XIII and liver transglutaminase also shared similar binding sites on fibrinogen, the A alpha- and the B beta-chains. The binding characteristics of liver transglutaminase were thus similar to Factor XIII binding to fibrin, but there were also important differences. Scatchard analyses of the binding data indicated that the affinity of liver transglutaminase (Kd = 4.17 x 10(-7) M) was at least 40-fold weaker compared with the affinity of Factor XIII to fibrinogen. Consequently, a 20-fold molar excess of Factor XIII a-chains specifically and completely inhibited the binding of liver transglutaminase to des-A-fibrinogen. The association between liver transglutaminase and fibrin(ogen) was also critically controlled by the conformational states of the two proteins. Substances capable of altering the conformation of either transglutaminase (such as guanosine 5'-triphosphate) or of fibrinogen (such as the tetrapeptide Gly-Pro-Arg-Pro and Fragment D) disrupted binding. Excess CaCl2 was able to counteract the effects of guanosine 5'-triphosphate on transglutaminase binding to fibrin. In contrast, Factor XIII binding to fibrin was unaffected by either guanosine 5'-triphosphate, CaCl2, or Gly-Pro-Arg-Pro, suggesting a more stable association between the two proteins. The physiologic implications of transglutaminase-fibrin(ogen) interactions are discussed.

Animals↗
PubMed1993

Site-directed mutagenesis of human tissue transglutaminase: Cys-277 is essential for transglutaminase activity but not for GTPase activity.

Transglutaminases (EC 2.3.2.13) catalyze an acyl-transfer reaction between peptide-bound glutamine residues and primary amines, including the epsilon-amino group of lysine residues in protein. Purified human erythrocyte transglutaminase was found to have another activity, i.e., GTP hydrolysis. Treatment of the enzyme with iodoacetamide, a cysteine-directed reagent, caused a 94% loss of TGase activity within 8 min, but no significant loss of GTPase activity. Cys-277, a known residue which is selectively modified by iodoacetamide, was replaced with Ser by site-directed mutagenesis to assess the role of the Cys-277 in the transglutaminase/GTPase activities. Wild-type cDNA, coding for human endothelial cell transglutaminase, and its C277S-mutated cDNA were cloned into a plasmid vector that contained a promoter from phage T7, and then expressed in Escherichia coli. The wild-type recombinant enzyme was indistinguishable from human erythrocyte transglutaminase in mobility on a SDS-polyacrylamide gel, immunoreactivity and catalytic activities for transglutaminase and GTPase. However, the recombinant enzyme was not blocked at the N-terminal alanine residue, as is the case in the naturally occurring erythrocyte enzyme. The C277S mutant enzyme showed no transglutaminase activity, but had Km and kcat values for GTPase activity that were comparable to those of wild-type recombinant and natural erythrocyte enzymes. These results demonstrate that Cys-277 is essential for transglutaminase activity, but not for GTPase activity, and that N-terminal blocking of tissue-type transglutaminase is not critical for either transglutaminase or GTPase activities.

Binding Sites↗
PubMed1990

Expression of guinea-pig liver transglutaminase cDNA in Escherichia coli. Amino-terminal N alpha-acetyl group is not essential for catalytic function of transglutaminase.

Transglutaminases (EC 2.3.2.13) catalyze the formation of epsilon-(gamma-glutamyl)lysine cross-links and the substitution of a variety of primary amines for the gamma-carboxamide groups of protein-bound glutamine residues. These enzymes are involved in many biological phenomena. Transglutaminase reactions also have been shown to be suitable for applied enzymology. In this study, as a first step of studies to elucidate the structure/function relationship of transglutaminase, we constructed an expression plasmid, pKTG1, containing a cDNA of guinea-pig liver transglutaminase between the NcoI and PstI sites of an expression vector, pKK233-2, and produced the liver transglutaminase as an unfused protein in Escherichia coli. The purified recombinant enzyme was indistinguishable from natural liver transglutaminase in some structural properties such as molecular mass, amino acid composition, and amino- and carboxyl-terminal sequences. However, the alpha-amino group of the amino-terminal alanine residue of the recombinant transglutaminase was not acetylated as was that of the natural enzyme. Comparison of the recombinant enzyme with the natural one did not indicate significant differences in specific activity and apparent Km values for substrates in the histamine incorporation into acetyl alpha s1-casein. The sensitivity to activation by Ca2+ and the rate of catalyzed protein cross-linking were also similar between recombinant and natural transglutaminases. These results indicated that the N alpha-acetyl group in natural liver transglutaminase has not a particular role in the catalytic function of this enzyme.

Acetylation↗
PubMed1998

Isolation of a cDNA encoding a novel member of the transglutaminase gene family from human keratinocytes. Detection and identification of transglutaminase gene products based on reverse transcription-polymerase chain reaction with degenerate primers.

We developed a method using a single set of degenerate oligonucleotide primers for amplification of the conserved active site of transglutaminases by reverse transcription-polymerase chain reaction (RT-PCR) and identification of the PCR products by cleavage with diagnostic restriction enzymes. We demonstrate amplification of tissue transglutaminase (TGC), keratinocyte transglutaminase (TGK), prostate transglutaminase (TGP), the a-subunit of factor XIII, and band 4.2 protein from different human cells or tissues. Analysis of normal human keratinocytes revealed expression of a transglutaminase different from the expected and characterized transglutaminase gene products. A full-length cDNA for the novel transglutaminase (TGX) was obtained by anchored PCR. The deduced amino acid sequence encoded a protein with 720 amino acids and a molecular mass of approximately 81 kDa. A comparison of TGX to the other members of the gene family revealed that the domain structure and the residues required for enzymatic activity and Ca2+ binding are conserved and showed an overall sequence identity of about 35%. Two transcripts with an apparent size of 2.2 and 2.8 kilobases were detected with a specific probe for TGX on Northern blots of human foreskin keratinocyte mRNA, indicating the presence of alternatively spliced mRNAs. cDNA sequencing revealed a shorter TGX transcript lacking the sequence homologous to that encoded by exon III of other transglutaminase genes. TGX expression increased severalfold when keratinocyte cultures were induced to differentiate by suspension or growth to postconfluency, suggesting that TGX contributes to the formation of the cornified envelope.

Amino Acid Sequence↗
PubMed1998

Induction of tissue transglutaminase by dexamethasone: its correlation to receptor number and transglutaminase-mediated cell death in a series of malignant hamster fibrosarcomas.

Treatment of the hamster fibrosarcoma cell lines (Met B, D and E) and BHK-21 hamster fibroblast cells with the glucocorticoid dexamethasone led to a powerful dose-dependent mRNA-synthesis-dependent increase in transglutaminase activity, which can be correlated with dexamethasone-responsive receptor numbers in each cell line. Increasing the number of dexamethasone-responsive receptors by transfection of cells with the HG1 glucocorticoid receptor protein caused an increase in transglutaminase activity that was proportional to the level of transfected receptor. In all experiments the levels of the tissue transglutaminase-mediated detergent-insoluble bodies was found to be comparable with increases in transglutaminase activity. Despite an increase in detergent-insoluble body formation, an increase in apoptosis as measured by DNA fragmentation was not found. Incubation of cells with the non-toxic competitive transglutaminase substrate fluorescein cadaverine led to the incorporation of this fluorescent amine into cellular proteins when cells were damaged after exposure to trypsin during cell passage. These cross-linked proteins containing fluorescein cadaverine were shown to be present in the detergent-insoluble bodies, indicating that the origin of these bodies is via activation of tissue transglutaminase after cell damage by trypsinization rather than apoptosis per se, since Met B cells expressing the bcl-2 cDNA were not protected from detergent-insoluble body formation. We describe a novel mechanism of cell death related to tissue transglutaminase expression and cell damage.

Animals↗
PubMed1999

A transglutaminase immunologically related to tissue transglutaminase catalyzes cross-linking of cell wall proteins in Chlamydomonas reinhardtii.

The addition of primary amines to the growth medium of the unicellular green alga Chlamydomonas reinhardtii disrupts cell wall assembly in both vegetative and zygotic cells. Primary amines are competitive inhibitors of the protein-cross-linking activity of transglutaminases. Two independent assays for transglutaminase confirmed a burst of extracellular activity during the early stages of cell wall formation in both vegetative cells and zygotes. When non-inhibiting levels of a radioactive primary amine ((14)C-putrescine) were added to the growth medium, both cell types were labeled in a reaction catalyzed by extracellular transglutaminase. The radioactive label was found specifically in the cell wall proteins of both cell types, and acid hydrolysis of the labeled material released unmodified (14)C-putrescine. Western blots of the proteins secreted at the times of maximal transglutaminase activity in both cell types revealed a single highly cross-reactive 72-kD band when screened with antibodies to guinea pig tissue transglutaminase. Furthermore, the proteins immunoprecipitated by this antiserum in vivo exhibited transglutaminase activity. We propose that this transglutaminase is responsible for an early cell wall protein cross-linking event that temporally precedes the oxidative cross-linking mediated by extracellular peroxidases.

Animals↗
PubMed1985

Retinoic acid-induced transglutaminase in mouse epidermal cells is distinct from epidermal transglutaminase.

Elevated transglutaminase activity and formation of cornified envelopes are markers of terminal differentiation in mouse epidermal cells. Epidermal transglutaminase catalyzes cornified envelope formation and in cultured cells is inducible by calcium ion or phorbol ester tumor promoters. Retinoic acid also induces transglutaminase activity but inhibits cross-linked envelope formation. This apparent paradox might be resolved by the observation that the retinoic acid-induced transglutaminase appears to be either a different enzyme or a markedly altered form of the epidermal enzyme. The retinoic acid-induced transglutaminase is soluble in aqueous buffers, is thermolabile at pH 9.0, 37 degrees C, and elutes from an anion exchange column at 0.4 M NaCl. In contrast, the epidermal enzyme is particulate and requires detergent for solubilization, is relatively thermostable, and elutes from the anion exchanger at 0.25 M NaCl. The retinoic acid-induced enzyme is probably identical with the "tissue" transglutaminase present in liver and in other cells. It is proposed that the transglutaminase induced by retinoic acid may play a role in the inhibition by retinoids of calcium and tumor promoter-induced differentiation.

Acyltransferases↗
PubMed1993

Type-2 plasminogen-activator inhibitor is a substrate for trophoblast transglutaminase and factor XIIIa. Transglutaminase-catalyzed cross-linking to cellular and extracellular structures.

Plasminogen-activator inhibitor type-2 (PAI-2), a serine-proteinase inhibitor, suppresses fibrinolysis by blocking both urokinase and tissue-type plasminogen activators. The 43-kDa PAI-2 molecule is an abundant cytosolic protein in certain cell types, but can upon appropriate stimulation be secreted as an approximately 60-70-kDa glycoprotein. However, in trophoblast membranes PAI-2 activity is associated with large covalent complexes (Jensen, P. H., Nykjaer, P., Andreasen P. A., Lund, L., Astedt, B. Lecander, I & Gliemann, J. (1989) Biochim. Biophys. Acta 986, 135-140). This study shows that PAI-2 can act as a substrate for both tissue transglutaminase and activated plasma factor XIII. In the presence of Ca2+, either of these will catalyze the incorporation of primary amines, such as putrescine, into PAI-2. Moreover, in reactions with tissue transglutaminase, PAI-2 homopolymers and, in conjunction with other biological substrates, heteropolymers were observed. As judged by the test of incorporating 125I-urokinase into SDS-resistant 125I-urokinase/PAI-2 complexes, polymerized PAI-2 retained its inhibitory activity. Furthermore, syncytiotrophoblast microvillous membranes and trophoblast detergent extracts incorporated 125I-PAI-2 into large structures in a reaction inhibited by putrescine and a synthetic inhibitor of transglutaminase. Trophoblast transglutaminase was identified as a tissue transglutaminase by non-denaturing gel electrophoresis and dansylcadaverine activity staining, fibronectin binding and Western blotting with a specific antibody. The transglutaminase-catalyzed and Ca(2+)-dependent anchoring of PAI-2 to extracellular membrane structures might have the purpose of focally regulating fibrinolysis.

Animals↗
PubMed1986

Cellular transglutaminase. Lung matrix-associated transglutaminase: characterization and activation with sulfhydryls.

Transglutaminase in the rat lung is tightly associated with the insoluble matrix which is not extractable with detergent, 0.5 M NaCl, and 40% glycerol solutions. The insoluble matrix was found to be rich in heparin sulfate and poor in collagen, elastin, and DNA. The lung transglutaminase was found to be distinct from tissue transglutaminase (identifiable with the well-characterized guinea pig liver transglutaminase) in its retention volume in DEAE-Sephacel columns and its Kd value in gel-filtration columns. The enzyme was activated 6-8-fold with the sulfhydryl reagent dithiothreitol. This activation was accompanied with the dissociation of enzyme from the tightly bound insoluble matrix and resulted in changes of the molecular properties of the enzyme--increase in affinity for anion-exchanger and decrease in Stokes radius. Addition of 50 mM KSCN induced a 2-fold increase in SH-dependent activation of transglutaminase activity. These results suggest that sulfhydryl agents may play a role in the activation and compartmental translocation of the transglutaminase in the lung.

Animals↗
PubMed1986

Localization of a liver transglutaminase and a large molecular weight transglutaminase substrate to a distinct plasma membrane domain.

Rat liver plasma membranes contain transglutaminase activity and a large molecular weight protein aggregate that serves as a substrate for this enzyme (Slife, C.W., Dorsett, M.D., Bouquett, G.T., Register, A., Taylor, E., and Conroy, S. (1985) Arch. Biochem. Biophys. 241, 329-336; Slife, C.W., Dorsett, M.D., and Tillotson, M.L. (1986) J. Biol. Chem. 261, 3451-3456). When purified plasma membranes were sonicated and the different plasma membrane domains were separated by sedimentation through a linear sucrose gradient, virtually all of the transglutaminase activity and the large molecular weight transglutaminase substrate were associated with membrane fragments which migrated to a very dense region of the gradient (1.18 g/cm3). The bile canalicular markers, 5'-nucleotidase and HA-4 antigen, were predominantly found at 1.11 g/cm3, while most of the sinusoidal/lateral marker, CE-9 antigen, was detected at 1.14 g/cm3. Smooth membrane vesicles were observed chiefly at the lighter densities upon morphological analysis, while many filament-bearing, plasma membrane segments and junctional complexes were contained in the heavy transglutaminase fractions. These data show that the plasma membrane transglutaminase and the large molecular weight transglutaminase substrate are associated with a distinct region of the plasma membrane.

Animals↗
PubMed1994

Structure and organization of the human transglutaminase 3 gene: evolutionary relationship to the transglutaminase family.

The human haploid genome contains a family of at least five different transglutaminases that are differentially expressed in time- and tissue-specific ways. Of these, transglutaminase 3 (TGase3) is unusual in that it is a pro-enzyme requiring activation by proteolysis. To date it is known to be expressed only in terminally differentiating epidermal and hair follicle keratinocytes. In this paper we show that it is encoded by a gene (TGM3) of 42.8 kbp containing 13 exons. In the course of isolation of genomic clones for the TGM3 gene, we also found clones encoding the widely expressed tissue or TGase2 enzyme, perhaps due to high degrees of sequence homology. The structure of the TGM2 gene has not yet been reported. Our incomplete data suggest its exon/intron organization is very similar to that of TGM3. Although the common intron splice points of all members of the transglutaminase gene family have been conserved, the TGM3 and TGM2 genes, and the gene for the subplasma membrane transglutaminase-like protein band 4.2, lack two introns found in the TGM1 and factor XIIIa genes, and the exact intron splice point of another intron is shifted with respect to that of the TGM1 and factor XIIIa genes. Based on sequence homologies and gene structures, the data support a phylogenic tree in which the TGM2 and TGM3 genes belong on a branch distinct from other transglutaminases.

Base Sequence↗
PubMed1986

Cellular transglutaminase. The particulate-associated transglutaminase from chondrosarcoma and liver: partial purification and characterization.

A transglutaminase from the malignant chondrocytes, rat swarm chondrosarcoma cells, was partially purified and characterized in an effort to understand transformation-induced changes in its activity. This enzyme separated by DE52 column chromatography after extraction from the particulate fraction of cell lysate was found to be distinct from previously characterized transglutaminases in its electrophoretic mobility, molecular size, substrate specificity, and immunologic reactivity. This enzyme was identified as a transglutaminase by its catalysis of amine (putrescine, spermine) incorporation at the carboxamide group of protein-bound gamma-glutamyl residues, and accordance of its kinetic data with the modified double displacement mechanism described for other transglutaminases. Limited proteolysis of the isolated enzyme resulted in a 3-4-fold increase of catalytic activity and a concomitant reduction of molecular size by approximately one-half. Incubation of labeled amine with chondrosarcoma cell lysate resulted in labeling of only a few proteins that appeared to be extensively cross-linked and that were located mostly in the particulate fraction of the cells. Transglutaminase extracted from the rat liver particulate fraction displayed enzymatic and structural properties closely resembling those of the enzyme from chondrosarcoma cells.

Alkylation↗
PubMed1987

High-performance liquid chromatographic assay of transglutaminase and its application to the purification of human erythrocyte transglutaminase and platelet factor XIII.

A high-performance liquid chromatographic method was developed for the assay of transglutaminase [EC 2.3.2.13] activity. Casein and dansylcadaverine were used as substrates and the reaction was stopped by adding an excess amount of EGTA. Casein-bound dansylcadaverine was separated from free dansylcadaverine by high-performance liquid chromatography on a TSK SW gel column on the basis of the differences in the molecular weight and hydrophobicity. The sensitivity was approximately 0.04 nmol of casein-bound dansylcadaverine in the assay mixture. With this assay method, human erythrocyte transglutaminase and platelet factor XIII were purified by successive chromatographies on DEAE-cellulose and Sephacryl S-300, which were common for both enzymes, followed by Blue Sepharose CL-6B and DEAE Bio-Gel A for erythrocyte transglutaminase or Phenyl-Sepharose CL-4B for platelet factor XIII. The purification factors and activity yields were 15,300-fold and 22% for erythrocyte transglutaminase and 43.8-fold and 33% for platelet factor XIII.

Blood Platelets↗
PubMed2001

Distinct characteristic of Galpha(h) (transglutaminase II) by compartment: GTPase and transglutaminase activities.

Galpha(h) (transglutaminase II) is a bifunctional enzyme possessing transglutaminase and GTPase activities. To better understand the factors affecting these two functions of Galpha(h), we have examined the characteristics of purified Galpha(h) from membrane and cytosol. GTP binding activity of mouse heart Galpha(h) was higher in membrane than that from cytosol. Furthermore, phospholipase C-delta1 (PLC-delta1) activity and coimmunoprecipitation of Galpha(h)-coupled PLC-delta1 in the alpha(1)-adrenoceptor-Galpha(h)-PLC-delta1 complex preparations were increased by phenylephrine in the presence of membranous Galpha(h). On the other hand, transglutaminase activity of cytosolic Galpha(h) was higher than that from membrane Galpha(h). These results demonstrate that bifunctions of Galpha(h) are regulated by its localization that can reflect the cellular functions of Galpha(h).

Animals↗