serpin family B member 8, cytoplasmic antiproteinase 2
Cytoplasmic antiproteinase 2 (CAP-2 or peptidase inhibitor 8/PI-8) is a member of the ovalbumin family of serpins (ov-serpins). Serpin B8 is produced by platelets and can bind to and inhibit the function of furin, a serine protease involved in platelet functions. In addition, this protein has been found to enhance the mechanical stability of cell-cell adhesion in the skin, and defects in this gene have been associated with an autosomal-recessive form of exfoliative ichthyosis. Diseases associated with SERPINB8 include Peeling Skin Syndrome 5 and Exfoliative Ichthyosis. Among its related pathways are Response to elevated platelet cytosolic Ca2+ and CFTR-dependent regulation of ion channels in Airway Epithelium (norm and CF). The ov-serpins are a family of closely related proteins, whose members can be secreted (ovalbumin), cytosolic (leukocyte elastase inhibitor, LEI), or targeted to both compartments (plasminogen activator inhibitor 2, PAI-2). It also characterized by N- and C-terminal extensions, the absence of a signal peptide, and a Ser rather than an Asn residue at the penultimate position. The ov-serpins corresponds to clade B 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 can cause 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, RCL 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.",