SOLUBILIZATION OF GAMMA-AMINOBUTYRIC ACID RECEPTOR PROTEIN FROM MAMMALIAN BRAIN

Radioactive gamma-aminobutyric acid and muscimol bind to two classes of sites in fractions of bovine brain, with KD values for gamma-aminobutyric acid of 28 nM and 150 nM and for muscimol of 3 nM and 21 nM; the maximum binding was 0.6 and 1.1 pmol/mg protein respectively for both ligands. Binding activity was solubilized by deoxycholate detergent, with 20-30% yield, assayed by rapid mini-gel filtration columns. Soluble muscimol binding had an apparent KD of 41 nM and capacity of 0.6 pmol/mg, and was inhibited competitively by gamma-aminobutyric acid (KI = 68 nM) and by other receptor-specific ligands. Gel filtration revealed a major peak of binding activity with apparent molecular weight of 900,000. © 1979.