THE HUMAN METABOTROPIC GLUTAMATE-RECEPTOR-8 (GRM8) GENE - A DISPROPORTIONATELY LARGE GENE LOCATED AT 7Q31.3-Q32.1

Metabotropic glutamate receptors (GRMs), which constitute a family of genes, are neurotransmitter receptors that respond to glutamate stimul ations by activating GTP-binding proteins and modulating second-messen ger cascades. Pharmacological and expression studies of the rodent Grm 8 gene suggest it could be a presynaptic receptor modulating glutamate release at the axon terminals. To study human GRM8, we have determine d its nucleotide sequence and genomic organization. While the coding r egion of the gene spans only 2.3 kb, the gene encompasses approximatel y 1000 kb of DNA at the boundary of the q31.3-q32.1 bands of chromosom e 7. This observation is relevant to the study of Smith-Lemli-Opitz sy ndrome and an autosomal dominant form of retinitis pigmentosa (RP10), since they map to the same region. (C) 1997 Academic Press.