At the inner mitochondrial membrane (IM), the phospholipase A2 group IV alpha (PLA2G4A) protein hydrolyzes monolysocardiolipin (MLCL) and produces dilysocardiolipin (DLCL) (Buckland et al. 1998, Sharp et al. 1994).
Once bound to the membrane, cPLA2 hydrolyzes phosphatidylcholine to produce arachidonic acid (AA), a precursor to inflammatory mediators. While several phospholipases can catalyze this reaction in cells overexpressing the enzymes, PLA2G4A is the major enzyme that catalyzes this reaction in vivo (Reed et al. 2011). At the same time, possible physiological roles have been described for soluble phospholipases (sPLA) in the mobilization of arachidonic acid in some cell types or under some physiological conditions (Murakami et al. 2011). Here, the major role of PLA2G4A has been annotated.
At the endoplasmic reticulum (ER) membrane, phosphatidylglycerol (PG) is hydrolyzed, and has one of its acyl chains cleaved off, by cytosolic phospholipase A2 alpha/beta/delta/zeta (PLA2G4A/B/D/F) (Ghomashchi et al. 2010) to form 1-acyl lysophosphatidylglycerol (LPG).
At the endoplasmic reticulum (ER) membrane, phosphatidic acid (PA) is hydrolyzed, and has one of its acyl chains cleaved off, by phospholipase A2 alpha/beta/delta/zeta (PLA2G4A/B/D/F) to form 1-acyl lysophosphatidic acid (LPA) (Ghomashchi et al. 2010).
At the outer mitochondrial (OM) membrane, phosphatidic acid (PA) is hydrolyzed, and has one of its acyl chains cleaved off, by phospholipase A2 alpha/beta/delta/zeta (PLA2G4A/B/D/F) to form 1-acyl lysophosphatidic acid (LPA) (Ghomashchi et al. 2010).
At the endoplasmic reticulum (ER) membrane, phosphatidylserine (PS) is hydrolyzed, and has one of its acyl chains cleaved off, by cytosolic phospholipase A2 alpha/beta/delta/epsilon/zeta (PLA2G4A,B,D/E/F) (Ghomashchi et al. 2010), or by group XVI phospholipase A2 (PLA2G16) (Duncan et al. 2008). This produces 1-acyl lysophosphatidylserine (LPS).
At the endoplasmic reticulum (ER) membrane, phosphatidylethanolamine (PE) is hydrolyzed, and has one of its acyl chains cleaved off by cytosolic phospholipase A2 alpha/delta/epsilon/zeta (PLA2G4A/D/E/F) (Ghomashchi et al. 2010). This produces 2-acyl lysophosphatidylethanolamine (LPE). Cytosolic phospholipase A2 enzymes show not only PLA2 hydrolyzing activity to form the 1-acyl lysophospholipid but also have a degree of PLA1 activity, producing a 2-acyl lysophospholipid.
At the endoplasmic reticulum (ER) membrane, phosphatidylserine (PS) is hydrolyzed, and has one of its acyl chains cleaved off, by cytosolic phospholipase A2 alpha/delta/zeta (PLA2G4A/D/F) (Ghomashchi et al. 2010). This produces 2-acyl lysophosphatidylserine (LPS). Cytosolic phospholipase A2 enzymes show not only PLA2 hydrolyzing activity to form the 1-acyl lysophospholipid but also have a degree of PLA1 activity, producing a 2-acyl lysophospholipid.
At the endoplasmic reticulum (ER) membrane, phosphatidylcholine (PC) is hydrolysed, and has one of its acyl chains cleaved off, by cytosolic phospholipase A2 alpha/beta/delta/epsilon/zeta (PLA2G4A/B/D/E/F) (Ghomashchi et al. 2010). This produces 2-acyl lysophosphatidylcholine (LPC). Cytosolic phospholipase A2 enzymes show not only PLA2 hydrolysing activity to form the 1-acyl lysophospholipid but also have a degree of PLA1 activity, producing a 2-acyl lysophospholipid.
At the endoplasmic reticulum (ER) membrane, 2-acyl lysophosphatidylcholine (LPC) is hydrolyzed to glycerophosphocholine (GPCho) by cytosolic phospholipase A2 alpha/beta/delta/epsilon/zeta (PLA2G4A/B/D/E/F) (Yamashita et al. 2005, Ghomashchi et al. 2010, Yamashita et al. 2009, Sharp et al. 1994) or by Phospholipase B1-like (PLBD1) (Xu et al. 2009). PLBD1 also acts as a phospholipase A2 but in addition has the propensity to hydrolyze the lysophospholipid formed in its initial reaction.