G protein-coupled receptor 15 is a protein that in humans is encoded by the GPR15 gene.
GPR15 is a class A orphan G protein-coupled receptor (heterotrimeric guanine nucleotide-binding protein, GPCR). The GPR15 gene is localized at chromosome 3q11.2-q13.1. It is found in epithelial cells, synovial macrophages, endothelial cells  and  lymphocytes especially T cells. 
From the mRNA sequence a 40.8 kD molecular weight of GPR15 is proposed. In an epithelial tumour cell line (HT-29), however, a 36 kD band, composed of GPR15 and galactosyl ceramide, was detected.  Protein expression in lymphocytes is strongly associated with hypomethylation of its gene.