Monitoring the interaction of a single G-protein key binding site with rhodopsin disk membranes upon light activation.
Heterotrimeric G-proteins interact with their G-protein-coupled receptors (GPCRs) via key binding elements comprising the receptor-specific C-terminal segment of the alpha-subunit and the lipid anchors at the alpha-subunit N-terminus and the gamma-subunit C-terminus. Direct information about diffusion and interaction of GPCRs and their G-proteins is mandatory for an understanding of the signal transduction mechanism. By using single-particle tracking, we show that the encounters of the alpha-subunit C-terminus with the GPCR rhodopsin change after receptor activation. Slow as well as less restricted diffusion compared to the inactive state within domains 60-280 nm in length was found for the receptor-bound C-terminus, indicating short-range order in rhodopsin packing.
Kim
Tai-Yang
TY
Physics Department, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
Uji-i
Hiroshi
H
Möller
Martina
M
Muls
Benoit
B
Hofkens
Johan
J
Alexiev
Ulrike
U
D001665:Binding Sites; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D008027:Light; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D012243:Rhodopsin / Q000378:metabolism*
D043562:Receptors, G-Protein-Coupled; D012243:Rhodopsin; D020962:Heterotrimeric GTP-Binding Proteins