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

G protein-coupled receptor family C group 5 member A (GPRC5A), also known as Retinoic acid-induced protein 3 (RAI3), is an orphan member of the Class C G protein-coupled receptor family (UniProt: Q8NFJ5). It is uniquely characterized by a short N-terminal extracellular domain, distinguishing it from other Class C members that typically possess large ligand-binding domains (NCBI Gene: 9052). GPRC5A is highly expressed in the lungs and is transcriptionally regulated by retinoic acid, playing a critical role in maintaining lung homeostasis (PubMed: 11033595). In clinical oncology, GPRC5A exhibits a dualistic nature: it functions as a tumor suppressor in lung cancer, where its deficiency promotes inflammation and malignancy, but acts as an oncogene in cancers of the pancreas, breast, and colon (PubMed: 17332320, 26334371). It modulates several key intracellular signaling cascades, including the EGFR, NF-kappaB, and STAT3 pathways, which influence cell proliferation and survival (PubMed: 21852466). Although no FDA-approved drugs currently target GPRC5A directly, it is being actively investigated as a biomarker for cancer progression and a potential target for novel small-molecule inhibitors or immunotherapy (PubMed: 30266100).

Other names

Retinoic acid-induced protein 3RAI3Retinoic acid-induced gene 1 proteinRAIG1GPCR5AOrphan G protein-coupled receptor PEIG-1

Modulation of EGFR, NF-kappaB, and STAT3 signaling pathways