PROTEINS ASSOCIATED WITH ALPHA-1-SUBUNIT-CONTAINING GABA(A) RECEPTORSFROM BOVINE BRAIN

In contrast to some other ion channels, there are at present no protei ns known that bind specifically to mature GABA(A) receptor channels. S uch proteins may be important for the structural organization and cyto skeletal anchoring of GABA(A) receptors and could also be expected to have channel modulatory effects. To identify proteins that are associa ted with naturally occurring GABA(A) receptors we immunoprecipitated t hese receptors from detergent-solubilized bovine brain membranes by an antibody directed against the alpha 1-subunit. Tubulin and actin were observed to coprecipitate specifically with the receptors. Nine addit ional proteins were detected, hinting at a complex protein network ass ociated with alpha-subunit-containing GABA(A) receptors. Results of a biochemical characterization of these GABA(A) receptor-tubulin complex -associated proteins (GTAPs) are presented here. Peptide mass fingerpr inting analysis and microsequencing of tryptic peptides indicated that at least three GTAPs have not been described until the present.