Document Type
Article
Publication Title
Journal of Biological Chemistry
Publication Date
10-2-1998
Volume
273
Issue
40
Disciplines
Biology | Life Sciences
Abstract
The stimulatory G protein α subunit G(sα) binds within a cleft in adenylyl cyclase formed by the α1-α2 and α3-β4 loops of the C2 domain. The pseudosymmetry of the C1 and C2 domains of adenylyl cyclase suggests that the homologous inhibitory α subunit G(iα) could bind to the analogous cleft within C1. We demonstrate that myristoylated guanosine 5'-3-O- (thio)triphosphate-G(iα1) forms a stable complex with the C1 (but not the C2) domain of type V adenylyl cyclase. Mutagenesis of the membrane-bound enzyme identified residues whose alteration either increased or substantially decreased the IC50 for inhibition by G(iα1). These mutations suggest binding of G(iα) within the cleft formed by the α2 and α3 helices of C1, analogous to the G(sα) binding site in C2. Adenylyl cyclase activity reconstituted by mixture of the C1 and C2 domains of type V adenylyl cyclase was also inhibited by G(iα). The C(1b) domain of the type V enzyme contributed to affinity for G(iα), but the source of C2 had little effect. Mutations in this soluble system faithfully reflected the phenotypes observed with the membrane-bound enzyme. The pseudosymmetrical structure of adenylyl cyclase permits bidirectional regulation of activity by homologous G protein α subunits.
DOI
https://doi.org/10.1074/jbc.273.40.25831
Rights
© 1998 by The American Society for Biochemistry and Molecular Biology, Inc.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Dessauer, Carmen W.; Tesmer, John J.G.; Sprang, Stephen R.; and Gilman, Alfred G., "Identification of a G(iα) binding site on type V adenylyl cyclase" (1998). Biological Sciences Faculty Publications. 531.
https://scholarworks.umt.edu/biosci_pubs/531