ISOLATION OF HYDROPHOBIC PROTEINS BINDING AMINO ACIDS: γ‐AMINOBUTYRIC ACID BINDING IN THE RAT CEREBRAL CORTEX

Abstract

Abstract —The binding of [ 14 C]GABA to nerve‐ending membranes isolated from rat cerebral cortex follows a hyperbolic curve saturating at 0·4pmol/μg protein. This binding is about 60% inhibited by chloropromazine, and about 40%, inhibited by bicuculline. A hydrophobic protein fraction binding [ 14 C]GABA was separated from the total. lipid extract of nerve‐ending membranes. The binding follows a hyperbolic curve that saturates at 10·5 pmol of [ 14 C]GABA/μg of protein, with an apparent K d = 30 μ m . The binding is competitively inhibited by bicuculline with a K i = 273 μ m . These results are compared with those previously obtained on a GABA binding protein from crustacean muscle.