The intensity of the tryptophan fluorescence of the α subunits of guanine nucleotide-binding regulatory proteins increases when they bind guanosine 5'-O-(3-thio)triphosphate (GTYγS). The kinetics of the fluorescence enhancement and of the measured binding of [35S]GTPγS are well correlated. The addition of Mg2+ to the nucleotide-bound proteins causes a further, rapid increase in the fluorescence intensity. Similar effects result from exposure of the proteins to F- and Mg2+, and the required concentration of F- is reduced by the inclusion of Al3+. It is presumed that the more highly fluorescent state of the G protein α subunits represents their active conformation.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - 1987|
ASJC Scopus subject areas