lysophosphatidic acid receptor 4, member of the class A family of seven-transmembrane G protein-coupled receptors
Lysophosphatidic acid receptor 4 (LPAR4) is a G protein-coupled receptor that binds and is activated by the bioactive lipid lysophosphatidic acid (LPA), which is released by activated platelets and constitutively found in serum. Phylogenetic analysis of the class A GPCRs shows that LAPR4 is classified into the cluster consisting receptors that are preferentially activated by adenosine and uridine nucleotides. Although LPA6 (P2Y5) is expressed in human hair follicle cells, LPA4 and LPA5 are not. These three receptors are highly homologous and mediate an increase in intracellular cAMP production. Activation of LPAR5 is coupled to G(12/13) proteins, leading to neurite retraction and stress fiber formation, whereas coupling to G(q) protein leads to increases in calcium levels.