The alcohol-binding pocket may also be involved in Gβγ-dependent activation. Mutation of a conserved Leu (GIRK2-L344, GIRK4*L339, GIRK1-L333, Fig. 8c) to Glu in the βL-βM ribbon of GIRK channels attenuates Gβγ activation17-19. We found that mutations in the βD-βE (L257) ribbon that altered alcohol-dependent activation also reduced Gβγ-dependent activation (Figs. 4 and 5). Together, these results suggest that conformational changes in the βD-βE and βL-βM structural elements, along with the N-terminal domain43,44, may be central to both alcohol-and Gβγ-dependent activation. Intriguingly, hydrophobic amino acids in the G protein Gβ subunit have been implicated in GIRK channel activation45, which perhaps interact directly with the alcohol-binding pocket in GIRK.
