Centerin, also known as germinal center B-cell-expressed transcript 1/GCET1, is a serpin whose expression is restricted to germinal center B-cells and lymphoid malignancies with germinal center B-cell maturation. Expression of centerin, together with bcl-6 and GCET2, constitutes a germinal center B-cell signature, which is associated with a good prognosis in diffuse large B-cell lymphomas. Centerin is thought to function in vivo in the germinal centre as an efficient inhibitor of a trypsin-like protease. It also inhibits the trypsin-like serine proteases trypsin, thrombin and plasmin and is able to bind heparin and DNA. The centerin gene maps to the A clade serpin cluster on chromosome 14q32.1, which also contains a1-antitrypsin and a1-antichymotrypsin together with seven other serpins. The clade A of the serpin superfamily includes the classical serine proteinase inhibitors, alpha-1-antitrypsin and alpha-1-antichymotrypsin, protein C inhibitor, kallistatin, and non-inhibitory serpins, like corticosteroid and thyroxin binding globulins. In general, SERine Proteinase INhibitors (serpins) exhibit conformational polymorphism shifting from native to cleaved, latent, delta, or polymorphic forms. Many serpins, such as antitrypsin and antichymotrypsin, function as serine protease inhibitors which regulate blood coagulation cascades. Non-inhibitory serpins perform many diverse functions such as chaperoning proteins or transporting hormones. Serpins are of medical interest because mutants have been associated with blood clotting disorders, emphysema, cirrhosis, and dementia. A classification based on evolutionary relatedness has resulted in the assignment of serpins to 16 clades designated A-P along with some orphans.
Comment:depending on the conformational state, the RC loop is surface accessible in the active form or buried and inserted as the central beta strand in the inactive form.
Jiyao W et al.(2023). "The conserved domain database in 2023.",