title: Monitoring the interaction of a single G-protein key binding site with rhodopsin disk membranes upon light activation.
abstract: 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.
authors.affiliation: Physics Department, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
authors.forename: Tai-Yang
authors.initials: TY
authors.lastname: Kim
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Uji-i
authors.forename: Martina
authors.initials: M
authors.lastname: Möller
authors.forename: Benoit
authors.initials: B
authors.lastname: Muls
authors.forename: Johan
authors.initials: J
authors.lastname: Hofkens
authors.forename: Ulrike
authors.initials: U
authors.lastname: Alexiev
mesh_terms: D001665:Binding Sites; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D008027:Light; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D012243:Rhodopsin / Q000378:metabolism*
chemical_list: D043562:Receptors, G-Protein-Coupled; D012243:Rhodopsin; D020962:Heterotrimeric GTP-Binding Proteins