Hydroxycarboxylic acid receptor 1
Hydroxycarboxylic acid receptor 1 (HCA), formerly known as G protein-coupled receptor 81 (GPR81), is a protein that in humans is encoded by the "HCAR1" gene. HCA, like the other hydroxycarboxylic acid receptors HCA and HCA, is a G protein-coupled receptor (GPCR). The primary endogenous agonist of HCA is lactic acid (and its conjugate base, lactate). Lactate activates HCA, which in turn inhibits lipolysis in fat cells.