GPRC5D notes

Deep research

• just deep-research-falcon human GPRC5D --fallback perplexity-lite failed (providers unavailable,
  2026-10-21). Notes from cached publications and UniProt Q9NZD1.

Function

• Orphan family C (metabotropic glutamate receptor-like) G protein-coupled receptor, RAIG4/group 5. "GPRC5D has
  seven putative transmembrane segments and is expressed in the cell membrane" PMID:11311935. 7TM, no identified
  ligand; UniProt FUNCTION: GPCR involved in hard keratin expression, role in hair/nail (PMID:15086536).
• Normally expressed only in the hair follicle; in multiple myeloma GPRC5D protein is on CD138+ plasma cells
  independent of BCMA, a validated cell-surface CAR-T/bispecific target PMID:30918115.
• Homodimer (UniProt, PubMed:38898050/39181182).
• IBA node PTN001025902 (GPRC5 family) carries protein kinase activator activity, signaling receptor complex and
  extracellular exosome, with donors GPRC5A/B (Q9NQ84/Q9NZH0).

Localization

• Seven-TM multi-pass membrane protein, extracellular N-terminus aa 1-27. Cell membrane PMID:11311935.
• Conclusion: plasma membrane, cell surface accessible (CAR-T/bispecific target). No surface-exposed large
  ectodomain beyond short loops, but the extracellular loops are the antibody epitopes.