G proteins: transducers of receptor-generated signals.

PERSPECTIVES AND SUMMARY .............................................................. 615 HISTORY ............................................................................................... 616 INDIVIDUAL G PROTEINS: FUNCTIONS AND MOLECULAR ENTITIES .......... 617 Criteria .for Involvement of a G Protein ..................................................... 618 Functions Regulated by G Proteins ........................................................... 619 Molecular Entities and Structure .............................................................. 622 LIGAND-G PROTEIN TERACTIONS ........................................................ 631 LIGAND-REGULATED PROTEIN-PROTEIN TERACTIONS ........................... 634 Receptor-G Protein Interactions ............................................................... 634 G Protein-Effector Interactions ................................................................ 638 G PROTEII~I-MEMBRANE INTERACTIONS .................................................. 643 COVALENT MODIFICATION F G PROTEINS ............................................ 644