QUANTITATIVE-ANALYSIS OF A CYSTEINE (351)GLYCINE MUTATION IN THE G-PROTEIN G(I1)ALPHA - EFFECT ON ALPHA(2A)-ADRENOCEPTOR-G(I1)ALPHA FUSION PROTEIN-ACTIVATION

Citation
Ic. Carr et al., QUANTITATIVE-ANALYSIS OF A CYSTEINE (351)GLYCINE MUTATION IN THE G-PROTEIN G(I1)ALPHA - EFFECT ON ALPHA(2A)-ADRENOCEPTOR-G(I1)ALPHA FUSION PROTEIN-ACTIVATION, FEBS letters, 428(1-2), 1998, pp. 17-22
Citations number
28
Categorie Soggetti
Biology,"Cell Biology",Biophysics
Journal title
ISSN journal
00145793
Volume
428
Issue
1-2
Year of publication
1998
Pages
17 - 22
Database
ISI
SICI code
0014-5793(1998)428:1-2<17:QOAC(M>2.0.ZU;2-3
Abstract
Fusion proteins mere constructed between the porcine alpha(2A)-adrenoc eptor and either wild-type (Cys(351)) Or a pertussis toxin-resistant ( Gly(351)) form of the G protein G(i1)alpha. Addition of adrenaline to membranes expressing the fusion proteins resulted in concentration-dep endent stimulation of their high affinity GTPase activity. The alpha(2 A)-adrenoceptor-wild type G(i1)alpha fusion protein produced substanti ally higher maximal stimulation of GTPase activity in response to adre naline than that containing Gly(351) G(i1)alpha. Treatment of the fusi on proteins as agonist-regulated enzymes allowed measurement of V-max and turnover number for adrenaline-stimulation of the GTPase activity of each fusion construct. The turnover number of the alpha(2A)-adrenoc eptor-Cys(351) Gly G(i1)alpha fusion protein was only 44% of that for the alpha(2A)-adrenoceptor-wild type G(i1)alpha fusion protein. These data provide the first direct quantitative evaluation of the effects o f a mutation of a G protein on the capacity of an agonist-occupied rec eptor to activate the mutant. (C) 1998 Federation of European Biochemi cal Societies.