The genes encoding the glutamate receptor subunit KA1 and KA2 (GRIK4 and GRIK5) are located on separate chromosomes in human, mouse, and rat

The chromosomal localization of the human and rat genes encoding the kainate-preferring glutamate receptor subunits KA1 and KA2 (GRIK4 and GRIK5, respectively) was determined by Southern analysis of rat x mouse and human x mouse somatic cell hybrid panels and by fluorescence in situ hybridization. The localization of the mouse genes (Grik4 and Grik5) was established by interspecific backcross mapping. GRIK4 and GRIK5 are located on separate chromosomes (Chrs) in all species. GRIK4 mapped to human Chr 11q22.3, mouse Chr 9, and rat Chr 8. GRIK5 mapped to human Chr 19q13.2, mouse Chr 7, and rat Chr 1. The genes encoding the (R,S)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-preferring subunit GluR4, or GluRD (GRIA4), the neural cell adhesion molecule (NCAM), the D2 dopamine receptor (DRD2), and the Thy-1 cell surface antigen (THY1) have all been previously mapped to the human Chr 11q22 region. The mapping of the human GRIK4 and GRIK5 genes confirms and extends the relationship between human Chr 11 and mouse Chr 9 and also human Chr 19 and mouse Chr 7. GRIK4 is the fifth gene shared by human Chr 11 and rat Chr 8, whereas GRIK5 is 1 out of the 12 genes that are located on both human Chr 19 and rat Chr 1. Our data extend the conserved synteny established between certain human, mouse, and rat Chrs.