Physiology
tTG is expressed ubiquitously. It requires calcium as a cofactor for transamidation activity. Transcription is increased by retinoic acid. Among its many supposed functions, it appears to play a role in wound healing, apoptosis, and extracellular matrix development
tTG is thought to be involved in the regulation of the cytoskeleton by crosslinking various cytoskeletal proteins including myosin, actin, and spectrin. Evidence shows that intracellular tTG crosslinks itself to myosin. It is also believed that tTG may stabilize the structure of the dying cells during apoptosis by polymerizing the components of the cytoskeleton, therefore preventing the leakage of the cellular contents into the extracellular space.
tTG also has GTPase activity: In the presence of GTP, it suggested to function as a G protein participating in signaling processes. Besides its transglutaminase activity, tTG is proposed to also act as kinase, and protein disulfide isomerase, and deamidase. This latter activity is important in the deamidation of gliadin peptides, thus playing important role in the pathology of coeliac disease.
Read more about this topic: Tissue Transglutaminase
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