Assignment of the human metabotropic glutamate receptor gene GRM4 to chromosome 6 band p21.3 by radiation hybrid mapping.

Metabotropic glutamate receptors (GRMs) are neurotransmitter receptors that respond to glutamate stimulation by activating GTP-binding protein and modulating second messenger cascades (Nakanishi, 1992). In particular GRM4, belonging to metabotropic receptors group III (Wu et al., 1998), has been suggested to mediate presynaptic action of glutamate in several brain areas by the inhibition of adenylate cyclase activity (Conn and Pin, 1997). GRM4 as been cloned from brain tissues, showing that it is strongly expressed in the cerebellum and at low levels in hippocampus, hypothalamus and thalamus (Flor et al., 1995, Makoff et al., 1996). GRMs may be involved in many neurological disorders and their chromosomal localizations may be important for linkage studies. To localize the human GRM4 gene on chromosome 6p21.3 we employed radiation hybrid (RH) panel analysis.