THE GAMMA-AMINOBUTYRIC-ACID RECEPTOR GAMMA-3 SUBUNIT GENE (GABRG3) IS TIGHTLY LINKED TO THE ALPHA-5 SUBUNIT GENE (GABRA5) ON HUMAN-CHROMOSOME 15Q11-Q13 AND IS TRANSCRIBED IN THE SAME ORIENTATION

GABA(A) receptors are heterooligomeric ligand-gated ion channels that mediate the effect of the inhibitory neurotransmitter gamma-aminobutyric acid. The GABA(A) receptors consist of at least 15 different receptor subunits that can be classified into 5 subfamilies (alpha, beta, gamma, delta, rho) on the basis of sequence similarity. Chromosomal mapping studies have revealed that several of the GABA(A) receptor subunit genes appear to be organized as clusters. One such cluster, which consists of the GABA(A) receptor beta 3 (GABRB3) and alpha 5 (GABRA5) subunit genes, is located in chromosome 15q11-q13. It is shown here that the GABA(A) receptor gamma 3 subunit gene (GABRG3) also maps to this region. Lambda and P1 phage clones surrounding both ends of GABRG3 were isolated; the clones derived from the 5' end of GABRG3 were linked to an existing phage contig spanning the 3' end of GABRA5. The two genes are located within 35 kb of each other and are transcribed in the same orientation. (C) 1995 Academic Press, Inc.