serpin family E member 1, plasminogen activator inhibitor-1
Plasminogen activator inhibitor-1 (PAI-1/PLANH1, also called endothelial PAI) is the primary, fast-acting inhibitor of plasminogen activators. It is often bound to vitronectin, an abundant component of the extracellular matrix in many tissues. PAI1 deficiency is a rare bleeding disorder that causes excessive or prolonged bleeding due to blood clots being broken down too early. PAI-1 is a member of the serpin superfamily and belongs to clade E. 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:1C5G_A; Human plasminogen activator inhibitor-1 latent-uncleaved and inserted
Structure:1DVM_A: Human PAI-1, active form, open/exposed RCL conformation
Jiyao W et al.(2023). "The conserved domain database in 2023.",