The effect of GDP on rod outer segment G-protein interactions.

摘要: The role of GDP has heretofore been little studied in the analysis visual receptor G-protein (G) interactions. Here we use kinetically resolved absorption and light scattering spectroscopy, centrifugation, porous membrane filtration, enzyme assay to compare effectiveness with that GTP or gamma-thio-guanosine-5'-triphosphate modulation binding rod disc membranes activated (R*). We also separation G alpha beta gamma subunits activation effector, cGMP phosphodiesterase. find when different nucleotide affinities are taken into account, actions such as release from R* binding, earlier ascribed alone, typical GDP. principal specific occur only weakly undetectably for are, respectively, solution While GDP, like GTP, releases receptor, argue cannot mediate subunit separation, even on surface. retained after hydrolysis may function prevent tight quiescent receptors a manner analogous its action receptors. Weak G.GDP accelerate catalyzed amplification during transduction.