BINDING OF GAMMA-AMINOBUTYRIC ACID(A) RECEPTORS TO TUBULIN

Tubulin cofractionated with gamma-aminobutyric acid(A) (GABA(A)) recep tors upon affinity chromatography on Affigel 15 coupled to the benzodi azepine Ro 7-1986, and this cofractionation was not due to unspecific adsorption of tubulin to the column material. In addition, GABA(A) rec eptors not only bound to microtubules but also coassembled with added tubulin through three cycles of microtubule polymerization and depolym erization. These data indicate that GABA(A) receptors may be associate d with the microtubule cytoskeleton in the brain. In an experiment des igned to detect a protein that possibly could form a bridge between tu bulin and the GABA(A) receptor, only a single protein band containing tubulin could be identified that was able to bind polymerized tubulin after sodium dodecyl sulfate-gel electrophoresis of affinity-purified GABA(A) receptors. These results are discussed with respect to a possi ble mechanism of association between GABA(A) receptors and microtubule s.