Identification, chromosomal location, and genome organization of mammalian G-protein-coupled receptors

Vertebrate G-protein-coupled receptors are encoded by a diverse multigene family. Thirteen distinct G-protein-coupled receptors (Gpcr) were cloned from mouse germline cDNA following amplification in the polymerase chain reaction (PCR) with degenerate oligonucleotide primers complementary to the third and sixth transmembrane domains. Eleven Gpcr clones were mapped to single sites in the mouse genome following interspecific backcross analysis. One clone was mapped to two sites and another was not polymorphic in the cross and could not be mapped. Gpcr loci were well dispersed throughout the mouse genome and mapped to chromosomes 1, 2, 3, 4, 5, 8, 9, 10, 13, 17, and 18. Six Gpcr clones likely represent mouse homologs of already identified receptors, one Gpcr clone may identify a third type of IL-8 receptor, and three Gpcr clones appear to encode novel G-protein-coupled receptors. Further, three factor crosses and Southern blot analyses demonstrated that Gpcr16 maps proximally within the Spr deletion on mouse chromosome 1, near the Vil and Bcg loci. Human chromosomal locations for most Gpcr loci could be predicted based on linkage homologies that have been identified between human and mouse. Mapping additional G-protein-coupled receptors against the panel of murine interspecific backcrosses should expand our understanding of mammalian Gpcr gene evolution and genome organization.