Abstract
We studied the selectivity of GABA B receptors for coupling to G proteins by testing the ability of various purified G proteins to increase GABA binding to N-ethylmaleimide (NEM)-treated membranes of bovine brain. The addition of G o, G ∗ o or g i1 to NEM-treated membranes increased GABA binding in a dose-dependent manner. However, the addition of G i2 did not elicit a marked increase in GABA binding. When α subunits of G proteins were mixed with various brain βγ subunit complexes composed of different γ subunits, and they were added to the NEM-treated membranes, G i2 with any βγ subunits hardly increased GABA binding. On the other hand, G o with any βγ subunits caused a marked increase, though G o with a small γ subunit was more effective than that with a large γ subunit. These data suggest that the selective coupling of the G proteins to GABA B receptors is determined by the α subunit.
Published Version
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