Findings from the last two years in signal transduction research, including the elucidation of the crystal structure of alpha1, the uncovering of multiple roles for lipidation, the mimicry of receptor action with peptides, and both the in vitro reconstitution of inhibition of adenylyl cyclase and the in cell reconstitution of receptor-G protein coupling in transient and stable expression studies, are integrated into a "current" view of the receptor --> G protein --> effector pathway. The question is raised whether receptor or betagamma is the nucleotide exchange factor, and the central participation of Mg2+ in G protein activation and the change in affinity of the G protein for Mg2+ during receptor-stimulated activation are stressed.