Recent Advances: Transglutaminase in Ocular Health and Pathological Processes

Transglutaminase (TG) is a big class of intraand extracellular enzymes with 9 members, all of which catalyze the formation of epsilon(γ-glutamyl) lysine isopeptide linkages between peptide substrates, except for a catalytically inactive member Band 4.1. These enzymes are tightly regulated, and involved in processes such as inflammation, reepithelialization, neovascularization and synthesis and stabilization of a fibrous extracellular matrix (ECM) [1]. Different types of TG are found in different cellular compartments. TG1 is located in the cytosolic and membrane compartments, whereas TG2 can additionally be found in the cell nucleus. As far as we know, TG3 and TG5 are restricted to the cytosolic compartment whereas certain forms of TG, such as TG4 and factor XIII are extracellular moieties [2].