Inhibition by pyridoxal-5′-phosphate of γ-aminobutyric acid receptor binding to synaptic membranes of cat cerebellum

Abstract

The binding of [ 3H]γ-aminobutyric acid to cat cerebellar membranes is reversibly inhibited in a competitive manner by pyridoxal-5′-phosphate present during the binding assay. Structural analogues of the inhibitor have no such effect. If, on the other hand, the membranes are preincubated with pyridoxal-5′-phosphate followed by the addition of sodium borohydride, a rapid, irreversible inhibition of subsequent γ-aminobutyric acid binding is observed. Since pyridoxal-5′-phosphate is known to inactivate certain enzymes by reacting with essential lysine residues, the present results suggest that such a lysine residue may be present within the γ-aminobutyric acid receptor.