G-PROTEINS

The family of heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins) serves an essential role in transducing receptor-generated signals across the plasma membrane. Recent findings reveal unexpected functional roles for individual G protein subunits. Thus, GTP-binding alpha-subunits and the betagamma-subunit complex can influence the activity of effector molecules independently or simultaneously, either synergistically or in opposition, to elicit a complex constellation of cellular events.