Protein Domain : Phospholipase A2 inhibitor, alpha/gamma type IPR016338

Type	Family
Description	This entry represents alpha- and gamma-type phospholipase A2 inhibitors (PLI) found in a variety of snakes, including Elapidae and Viperidae. Phospholipase A2 (PLA2; ) is a calcium-dependent enzyme that is involved in inflammatory processes such as the liberation of free arachidonic acid from the membrane pool for the biosynthesis of eicosanoids. Both Elapidae and Viperidae contain PLA2 enzymes in their venoms [ , ], which can exhibit a wide variety of pharmacological effects including neurotoxicity and myotoxicity. As a result, these snakes must contain PLI in their blood in order to protect themselves from leakage of their own venom PLA2s into the circulatory system. Venomous snakes have three distinct types of PLA2-inhibitory proteins: PLI-alpha, PLI-beta, and PLI-gamma. Alpha-type PLI (PLI-alpha) proteins have been found in a number of Viperidae snakes [ ]. Most PLI-alpha proteins are homomultimers composed of 3-5 subunits, except in Trimeresurus flavoviridis (Habu), where PLI-alpha consists of a trimer of two homologous subunits (PLI-alpha-A and PLI-alpha-B), each of which contains one C-type lectin-like domain and exhibiting significant homology to serum mannose-binding protein and lung-surfactant apoprotein []. A PLI-alpha homologue that lacks inhibitory activity was found in the non-venomous snake Elaphe quadrivirgata (Japanese four-lined ratsnake) [].Phospholipase A2 inhibitor CNF, a gamma-type PLI, inhibits the PLA2 activity of crotoxin (CTX) by replacing the acid subunit (CA) in the CTX complex [ ]. It has a proinflammatory action through activation of important main signalling pathways for human leukocytes, in vitro []. In mice phrenic nerve-diaphragm muscle preparations it abolishes both the muscle-paralyzing and muscle-damaging activities of CTX [].
Short Name	PLipase_A2-inh_a/b-type