GPRC5D Proteins (G-protein coupled receptor, class C group 5 member D)

Background

G-protein coupled receptor family C group 5 member D (GPRC5D) is a retinoic acid-inducible 40 kDa protein characterized by seven transmembrane segments and a concise N-terminal extracellular region. As a member of the retinoic acid inducible GPCR 1 (RAIG1) family, GPRC5D is located on human chromosome 12p13 and predominantly expressed in the cell membrane. Its expression patterns vary with high levels in the pancreas, medium concentrations in the kidney, small intestine, spleen, and testis, and low levels in tissues like the lung, colon, leukocyte, prostate, and thymus. Notably, GPRC5D expression is absent in the brain, heart, liver, placenta, skeletal muscle, and ovary.

Significantly, GPRC5D showcases a high and selective expression on the surface of CD138+ multiple myeloma (MM) cells. In contrast, its presence in normal tissues is considerably lower and confined mainly to effector B cells and certain keratinizing tissues. This distinct expression pattern positions GPRC5D as a valuable marker for monitoring MM tumor load and as a potential target for MM-specific T cell-engagement, including bispecific antibodies and CAR-T cells. Alternate splicing produces two isoforms with alterations in the cytoplasmic tail.

Synonyms

GPRC5D; MGC129713; MGC129714; orphan G-protein coupled receptor