|
KMID : 0624620080410070548
|
|
BMB Reports
2008 Volume.41 No. 7 p.548 ~ p.553
|
|
|
Affinity of transducin for photoactivated rhodopsin: dependence on nucleotide binding state
|
|
Clack James W.
|
|
|
Abstract
|
|
|
|
The interaction of the rod GTP binding protein, Transducin (Gt), with bleached Rhodopsin (R*) was investigated by measuring radiolabeled guanine nucleotide binding to and release from soluble and/or membrane-bound Gt by reconstituting Gt containing bound GDP (Gt-GDP) or the hydrolysis-resistant GTP analog guanylyl imidodiphosphate (Gt-p[NH]ppG) with R* under physiological conditions. Release of GDP and p[NH]ppG from Gt occurred to the same extent and with the same light sensitivity both in the presence and absence of added GTP. Significant amounts of Gt without bound nucleotide (Gt-) were generated. When ROS containing bleached rhodopsin (R*) were centrifuged in low ionic strength buffer, Gt- remained associated with the membrane fraction, whereas Gt-GDP remained in the soluble fraction. These results suggest that Gt-GDP and Gt-p[NH]ppG have similar affinities for R*. The results also suggest that Gt-, rather than Gt-GDP, is the moiety which exhibits tight, "light-induced" binding to rhodopsin. [BMB reports 2008; 41(7): 555-560]
|
|
|
KEYWORD
|
|
|
G proteins, Photoreceptors, Rhodopsin, Transduction
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
  
|
|