Contribution of each Trp residue toward the intrinsic fluorescence of the Giα1 protein.

ABSTRACT: Giα1 is the inhibitory G-protein that, upon activation, reduces the activity of adenylyl cyclase. Comparison of the crystal structures of Giα1 bound to GDP•AMF or GTPγS with that of the inactive, GPD-bound protein indicates that a conformational change occurs in the activation step centered on three switch regions. The contribution of each tryptophan residue (W211 in the switch II region, W131 in the α-helical domain, and W258 in the GTPase domain) toward the intrinsic protein fluorescence was evaluated by using W211F, W131F, and W258F mutants. All three tryptophan residues contributed significantly toward the emission spectra regardless of the conformation. When activated by either GDP•AMF or GTPγS, the observed maximal-fluorescence scaled according to the solvent accessibilities of the t

SUBMITTER: Najor MS 

PROVIDER: S-EPMC4287000 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature