cytosolic phospholipase A2; phospholipase A2 group IVA; includes: phospholipase A2; phosphatidylcholine 2-acylhydrolase; lysophospholipase (PLA2G4A, PLA2G4)

Function

• selectively hydrolyzes arachidonyl phospholipids in the sn-2 position releasing arachidonic acid
• together with its lysophospholipid activity, implicated in initiation of the inflammatory response
• stimulated by agonists such as ATP, EGF, thrombin & bradykinin as well as by cytosolic Ca+2
• activated by phosphorylation at both Ser-505 & Ser-727
• interacts with KAT5

phosphatidylcholine + H2O = 1-acylglycerophosphocholine + a carboxylate

2-lysophosphatidylcholine + H2O = glycerophosphocholine + a carboxylate

Kinetic parameters:

• Vmax=2.7 umol/min/mg enzyme for the phospholipase A2 reaction
• Vmax=4.6 umol/min/mg enzyme for the lysophosphatase reaction

Structure

• the N-terminal C2 domain
  • associates with lipid membranes upon Ca+2 binding
  • modulates enzyme activity by presenting the active site to its substrate in response to increases in cytosolic Ca+2
• contains 1 C2 domain
• contains 1 PLA2c domain

Compartment

• cytoplasm, cytoplasmic vesicle
• translocation from cytoplasm to membrane vesicles (Ca+2-dependent)

Expression

• expressed in macrophages, platelets, neutrophils, fibroblasts & lung endothelium

More general terms

• phospholipase-A2 [PLA2] type 4
• lysophospholipase

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=5321
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:5321
• OMIM: https://mirror.omim.org/entry/600522
• UniProt: http://www.uniprot.org/uniprot/P47712.html