Photoactivated conformational changes in rhodopsin: a time-resolved spin label study

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Science  26 Nov 1993:
Vol. 262, Issue 5138, pp. 1416-1419
DOI: 10.1126/science.8248781


Rhodopsin has been selectively spin-labeled near the cytoplasmic termini of helices C and G. Photoactivation with a light flash induces an electron paramagnetic resonance spectral change in the millisecond time domain, coincident with the appearance of the active metarhodopsin II intermediate. The spectral change is consistent with a small movement near the cytoplasmic termination of the C helix and reverses upon formation of the MIII state. These results provide an important link between the optical changes associated with the retinal chromophore and protein conformational states.