serpin family L, serpin family proteins from nematodes
The role of nematode serpins remains largely elusive. The only nematode serpin for which experimental evidence indicates an evasive function is Brugia malayi SPN-2 which specifically inhibits two human neutrophil-derived serine proteinases, cathepsin G and elastase. Less is known of Brugia malayi SPN-1, which is present at all stages of the parasite life cycle and could exist to inhibit a cognate proteinase endogenous to the parasite. Schistosoma serpins are hypothesized to play a role in both the physiological control of elastase within the schistosomes, and protection of the parasite from activated neutrophils during inflammation. Caenorhabditis elegans serpins are thought to regulate endogenous serine proteinases as well as inhibit proteinases produced by pathogenic microorganisms. 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.
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