The /-Aminobutyric Acid Receptor 1/3 Subunit Gene (GABRG3) Is Tightly Linked to the Subunit Gene (GABRA5) on Human Chromosome 15q11-q13 and Is Transcribed in the Same Orientation

GABAA receptors are heterool igomeric l igand-gated ion channels that mediate the effect of the inhibitory neurotransmitter T-aminobutyric acid. The GABAA re-ceptors consist of at least 15 different receptor sub-units that can be classified into 5 subfamil ies (a, fl, ~,, 3, p) on the basis of sequence similarity. Chromosomal mapping studies have revealed that several of the GABAA receptor subunit genes appear to be organized as clusters. One such cluster, which consists of the GABAA receptor f13 (GABRB3) and a5 (GABRA5) sub-unit genes, is located in chromosome 15q11-q13. It is shown here that the GABAA receptor T3 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 l inked to an exist ing 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. © 1995 Academic Press, Inc