Molecular cloning reveals the existence of a fourth γ subunit of the vertebrate brain GABAAreceptor

Abstract

We have isolated a cDNA, from the chicken, that encodes a fourth type of γ subunit of the vertebrate brain GABA_A receptor. The mature polypeptide (which we name γ4) displays 67%, 69% and 70% identity, respectively, to the rat γ1, γ2 and γ3 subunits. In the developing chicken brain, the γ4‐subunit mRNA is first detected at embryonic day 13; the transcript level then increases progressively during embryogenesis. In situ hybridization reveals that the γ4‐subunit mRNA is abundant in several brain regions, including the ectostriatum, nucleus rotundus and hyperstriatum ventrale, which are involved in visual processing and learning.