ABSTRACTWe have cloned and mapped the chromosomal location of three novel human genes encoding G protein-coupled receptors that we have named GPR6, GPR5, and GPR4. The entire coding region for each of these genes was contained on single exons. Gene GPR6 encoded a receptor that shared closest identity (71% in the transmembrane regions) with the human orphan receptor GPR3 and was localized to chromosome 6 (q21–q22.1). Northern blot analysis revealed that GPR6 transcripts were abundant in the human putamen and to a lesser extent in the frontal cortex, hippocampus, and hypothalamus. Gene GPR5 encoded a receptor that most closely resembled the orphan receptor RBS11 (48% in the transmembrane regions) and the MIP 1α/RANTES receptor (45% in the transmembrane regions) and was localized to chromosome 3 (p21.3–p21.1). Gene GPR4 shared identity (40% in the transmembrane regions) with the human platelet-activating factor receptor and was localized to chromosome 19 (q13.2–