Background of the antigen
GPRC6A (G protein-coupled receptor family C group 6 member A) is a 928 amino acid protein encoded by the mouse Gprc6a gene. GPRC6A is a member of the G protein-coupled receptor 3 family. This receptor is activated by both amino acids and extracellular concentration of calcium ions. The activity of GPRC6A is mediated by a G protein that activates a phosphatidylinositol-calcium second messenger system. GPRC6A senses changes in the extracellular concentration of calcium ions, suggesting that it may mediate extracellular calcium-sensing responses in osteoblasts. Osteocalin stimulates the activity of GPRC6A in the presence of calcium. GPRC6A also acts as a receptor for amino acids, with a preference for basic amino acids such as L-Lys, L-Arg and L-ornithine. Its affinity for amino acids suggests that it may act as a regulatory component of the urea cycle. GPRC6A is expressed at high levels in liver, lung, spleen and heart, and at lower levels in kidney, skeletal muscle and brain.