Thelysophospholipid receptor (LPL-R) group are members of theG protein-coupled receptor family ofintegral membrane proteins that are important forlipid signaling.[1] In humans, there are eleven LPLreceptors, each encoded by a separate gene. These LPL receptor genes are also sometimes referred to as "Edg" (an acronym forendothelial differentiation gene).
The ligands for LPL-R group are the lysophospholipid extracellularsignaling molecules,lysophosphatidic acid (LPA) andsphingosine 1-phosphate (S1P).
The termlysophospholipid (LPL) refers to anyphospholipid that is missing one of its two O-acyl chains. Thus, LPLs have a free alcohol in either the sn-1 or the sn-2 position. The prefix 'lyso-' comes from the fact that lysophospholipids were originally found to be hemolytic, however it is now used to refer generally to phospholipids missing an acyl chain. LPLs are usually the result ofphospholipase A-type enzymatic activity on regular phospholipids such asphosphatidylcholine orphosphatidic acid, although they can also be generated by the acylation of glycerophospholipids or the phosphorylation of monoacylglycerols. Some LPLs serve important signaling functions such aslysophosphatidic acid.
LPL receptor ligands bind to and activate theircognate receptors located in the cell membrane. Depending on which ligand, receptor, and cell type is involved, the activated receptor can have a range of effects on the cell. These include primary effects of inhibition ofadenylyl cyclase and release ofcalcium from theendoplasmic reticulum, as well as secondary effects of preventingapoptosis and increasingcell proliferation.[2]
The following is a list of the eleven known human LPL receptors:[1][3][4]
| Gene Symbol | IUPHAR Symbol | Gene / Protein Name | Agonist Ligand | Synonyms |
|---|---|---|---|---|
| LPAR1 | 272 | lysophosphatidic acid receptor 1 | LPA | EDG2 |
| LPAR2 | 273 | lysophosphatidic acid receptor 2 | " | EDG4 |
| LPAR3 | 274 | lysophosphatidic acid receptor 3 | " | EDG7 |
| LPAR4 | LPA4 | lysophosphatidic acid receptor 4 | " | GPR23 |
| LPAR5 | LPA5 | lysophosphatidic acid receptor 5 | " | GPR92 |
| LPAR6 | LPA6 | lysophosphatidic acid receptor 6 | " | P2RY5 |
| S1PR1 | 275 | sphingosine-1-phosphate receptor 1 | S1P | EDG1 |
| S1PR2 | 276 | sphingosine-1-phosphate receptor 2 | " | EDG5 |
| S1PR3 | 277 | sphingosine-1-phosphate receptor 3 | " | EDG3 |
| S1PR4 | 278 | sphingosine-1-phosphate receptor 4 | " | EDG6 |
| S1PR5 | 279 | sphingosine-1-phosphate receptor 5 | " | EDG8 |