HOW RECEPTORS TALK TO TRIMERIC G-PROTEINS

Stimulated by hormones and sensory stimuli, serpentine receptors promo te the release of GDP that is bound to the a subunit of trimeric G pro teins and its replacement by GTP. Recent investigations have begun to define the sizes, shapes, and relative orientations of receptors and G proteins, ?he surfaces through which they interact with one another, and conformational changes in both sets of molecules that underlie rec eptor-catalyzed guanine-nucleotide exchange.