serpin family F member 1, Pigment epithelium-derived factor (PEDF)
Pigment epithelium-derived factor (PEDF, also called capsin or EPC-1) is an extracellular component of the retinal interphotoreceptor matrix, vitreous humor, and aqueous humor of the adult eye. PEDF is non-inhibitory member of the serpin superfamily. It exhibits neurotrophic, neuroprotective and antiangiogenic properties and is widely expressed in the developing and adult nervous systems. This subgroup corresponds to clade F1 of the serpin superfamily. 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.
Structure:1IMV_A: Human PEDF in the native state, only part of RCL is visible but is clearly in open conformation
Jiyao W et al.(2023). "The conserved domain database in 2023.",