Journal of Biological Chemistry
Volume 271, Issue 43, 25 October 1996, Pages 26445-26448
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Gβ Subunit Interacts with a Peptide Encoding Region 956-982 of Adenylyl Cyclase 2: CROSS-LINKING OF THE PEPTIDE TO FREE Gβγ BUT NOT THE HETEROTRIMER*

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The region encoded by amino acids 956-982 of adenylyl cyclase 2 is important for Gβγ stimulation. Interactions of a peptide encoding the 956-982 region of adenylyl cyclase 2 (QEHAQEPERQYMHIGTMVEFAYALVGK (QEHA peptide)) with Gβγ subunits were studied. QEHA peptide was covalently attached to β subunit of free Gβγ by the cross-linker N-succinimidyl(4-iodoacetyl)aminobenzoate. Cross-linking was proportional to the amount of QEHA peptide added; other control peptides cross-linked minimally. When Go was used, very little cross-linking was observed with GDP and EDTA, but upon activation by guanosine 5′-3-O-(thio)triphosphate and Mg2+, specific cross-linking of the QEHA peptide to Gβ was observed. We conclude that β subunits of G proteins contain effector interaction domains that are occluded by Gα subunits in the heterotrimer. Molecular modeling studies used to dock the QEHA peptide on to Gβ indicate that amino acids 75-165 of Gβ may be involved in effector interactions.

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*

Supported by National Institutes of Health Grants DK38761 and GM54508 (to R. I.), DK37219 (to J. D. H.), and DA00060 (to H. W.) and by the Aaron Diamond Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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Aaron Diamond Fellow.