G protein-coupled receptor class C group 5 member A (GPRC5A)

G protein-coupled receptor class C group 5 member A (GPRC5A) is a member of the class C G protein-coupled receptor (GPCR) family, primarily expressed in lung and epithelial tissues[1][4]. Initially discovered as a retinoic acid-inducible gene, GPRC5A encodes a protein with seven transmembrane domains. It acts as a signal transducer and is involved in regulating cellular growth, epithelial cell differentiation, and cell adhesion. GPRC5A has a well-established role as a tumor suppressor in lung tissue: its loss or decreased expression is linked to tumor initiation and progression, whereas its dysregulation is observed in various cancers including lung, breast, colorectal, and pancreatic cancer[1][2]. GPRC5A participates in cAMP, NF-κB, STAT3, and FAK/Src signaling pathways, and its expression is tightly regulated by retinoic acid, p53, BRCA1, and other transcriptional/post-transcriptional mechanisms[1][2]. No specific drugs currently target GPRC5A clinically, though endogenous ligands may include tryptamine and indole-related compounds from gut microflora[4]. GPRC5A is being investigated as a cancer biomarker and as a potential future therapeutic target, but drug development is challenged by its orphan status and complex tissue-dependent functions[1][4].

Other names

Retinoic acid-induced protein 3Retinoic acid-inducible gene 1RAIG1RAI3Phorbol ester induced gene 1PEIG-1TPA induced gene 1Retinoic acid-induced gene 1 proteinTIG1orphan G-protein-coupling receptor PEIG-1

Drugs (if developed) would likely modulate signaling via G protein-coupled receptor pathways, affecting downstream signal transduction, cell proliferation, or apoptosis[1][2]