Effect of Al3+ plus F- on the Catecholamine-Stimulated GTPase Activity of Purified and Reconstituted Gs

Douglas R. Brandt, Elliott M. Ross

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Abstract

The effects of Al3+ and F- on the catecholamine-stimulated GTPase cycle were studied by using reconstituted phospholipid vesicles that contained purified β-adrenergic receptor and the stimulatory GTP-binding protein of the adenylate cyclase system, Gs. Al3+/F- activated reconstituted Gs to levels previously reported for detergent-solubilized, purified Gs, although both activation and deactivation were faster in the reconstituted preparation. Under these conditions, Al3+/F- did not inhibit by more than 15% the β-adrenergic agonist-stimulated GTPase activity of the vesicles nor did it significantly inhibit the rates of GTP binding, GTP hydrolysis, or GDP release. When Mg2+ (50 mM) was used instead of agonist to promote GTP hydrolysis in the receptor-Gs vesicles, Al3+/F- was found to inhibit GTPγS binding, GDP release, and steady-state GTPase activity to unstimulated levels. These data can be interpreted as indicating that the receptor catalyzes nucleotide exchange by Gs faster or more efficiently than does Mg2+.

Original languageEnglish (US)
Pages (from-to)7036-7041
Number of pages6
JournalBiochemistry
Volume25
Issue number22
DOIs
StatePublished - Nov 1986

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ASJC Scopus subject areas

  • Biochemistry

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