Group IVC cytoplasmic phospholipase A2; catalytic domain; Ca-independent
Group IVC cPLA2, a small 61 kDa protein, is a single domain alpha/beta hydrolase. It lacks a C2 domain; therefore, it has no Ca-dependence. Group IVC cPLA2 is also referred to as cPLA2-gamma. The cPLA2-gamma enzyme is predominantly found in cardiac and skeletal muscles, and to a lesser extent in the brain. Human cPLA2-gamma is approximately 30% identical to cPLA2-alpha. The catalytic domain of cytosolic phospholipase A2 (PLA2; EC 188.8.131.52) hydrolyzes the sn-2-acyl ester bond of phospholipids to release arachidonic acid. At the active site, cPLA2 contains a serine nucleophile through which the catalytic mechanism is initiated. The active site is partially covered by a solvent-accessible flexible lid. cPLA2 displays interfacial activation as it exists in both "closed lid" and "open lid" forms. Movement of the cPLA2 lid possibly exposes a greater hydrophobic surface and the active site. cPLA2 belongs to the alpha-beta hydrolase family which is identified by a characteristic nucleophile elbow with a consensus sequence of Sm-X-Nu-Sm (Sm = small residue, X = any residue and Nu = nucleophile). Includes PLA2G4C protein from human and Pla2g4c protein from mouse.