The transglutaminase family includes both intracellular and extracellular enzymes catalyzing Ca2+-dependent reactions which result in the post-translational modification of proteins at the level of glutamine and lysine. This post-translational modification leads to the formation of the e(g-glutamyl)lysine cross-links and/or to the covalent incorporation of polyamines into proteins. The formation of these covalent cross-links leads to the polymerization of substrate points which become very resistant to physical-chemical stress.
D'Amato, M., Iannicola, C., Monteriu, G., & Piacentini, M. (1999). Mapping and sequencing of the murine 'tissue' Transglutaminase (Tgm2) gene: Absence of mutations in MRLlpr/lpr mice . Cell Death and Differentiation, 6(3), 216-217. https://doi.org/10.1038/sj.cdd.4400494