Signaling by guanine nucleotide-binding proteins (G proteins) involves sequential protein-protein interactions. G protein-βγ subunit (Gβγ) interactions with phospholipase C-β2 (PLC-β2) were studied to determine if all Gβ contacts are required for signaling. A peptide encoding Gβ amino acid residues 86 to 105 stimulated PLC-β2. Six residues (96 to 101) within this sequence could transfer signals and thus constitute a core signal transfer region. Another peptide, encoding Gβ amino acid residues 115 to 135, did not substantially stimulate PLC-β2 by itself but inhibited Gβγ stimulation, indicating that residues 115 to 135 constitute a general binding domain. ResoLution of signal transfer regions from general binding domains indicates that all protein-protein contacts are not required for signal transfer and that it may be feasible to synthesize agonists and antagonists that regulate intracellular signal flow.