UniProt functional annotation for Q08188

UniProt code: Q08188.

Organism: Homo sapiens (Human).
Taxonomy: Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo.
 
Function: Catalyzes the calcium-dependent formation of isopeptide cross-links between glutamine and lysine residues in various proteins, as well as the conjugation of polyamines to proteins. Involved in the formation of the cornified envelope (CE), a specialized component consisting of covalent cross-links of proteins beneath the plasma membrane of terminally differentiated keratinocytes. Catalyzes small proline-rich proteins (SPRR1 and SPRR2) and LOR cross-linking to form small interchain oligomers, which are further cross-linked by TGM1 onto the growing CE scaffold (By similarity). In hair follicles, involved in cross- linking structural proteins to hardening the inner root sheath. {ECO:0000250}.
 
Catalytic activity: Protein glutamine + alkylamine = protein N(5)- alkylglutamine + NH(3). {ECO:0000255|PROSITE-ProRule:PRU10024, ECO:0000269|PubMed:11980702, ECO:0000269|PubMed:12679341}.
Cofactor: Name=Ca(2+); Xref=ChEBI:CHEBI:29108; Evidence={ECO:0000269|PubMed:11980702, ECO:0000269|PubMed:12679341}; Note=Binds 3 Ca(2+) cations per subunit. Binds 1 Ca(2+) as a zymogen, and binds 2 more Ca(2+) cations, or other divalent metal cations, after proteolytic processing. {ECO:0000269|PubMed:11980702, ECO:0000269|PubMed:12679341};
Subunit: Consists of two polypeptide chains, which are synthesized as a precursor form of a single polypeptide. {ECO:0000269|PubMed:11980702, ECO:0000269|PubMed:12679341}.
Ptm: Activated by proteolytic processing. In vitro activation is commonly achieved by cleavage with dispase, a neutral bacterial protease. Dispase cleavage site was proposed to lie between Ser- 470 and Ser-471 (PubMed:8099584) or between Pro-465 and Phe-466 (PubMed:16565075). Physiological activation may be catalyzed by CTSL and, to a lesser extent, by CTSS, but not by CTSB, CTSD nor CTSV (PubMed:16565075). {ECO:0000269|PubMed:16565075, ECO:0000269|PubMed:8099584}.
Similarity: Belongs to the transglutaminase superfamily. Transglutaminase family. {ECO:0000305}.

Annotations taken from UniProtKB at the EBI.