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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 fluorescence microscopy and single particle tracking we showed that the encounters of the alpha-subunit C-terminus with the GPCR rhodopsin change after receptor activation revealing inhomogeneous and restricted diffusion of the receptor (1). To obtain further information about the underlying membrane structure in the signaling state of rhodopsin we now constructed high-resolution transducin visits maps on rhodopsin disk membranes using the inherent information from the single molecule traces.(1) Kim, T.Y., Uji-i, H., Moeller, M., Muls, B., Hofkens, J. and Alexiev, U. Biochemistry48, 3801-3803(2009) |
