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Photoactivated Conformational Changes in Rhodopsin: A Time-Resolved Spin Label Study

1993; American Association for the Advancement of Science; Volume: 262; Issue: 5138 Linguagem: Inglês

10.1126/science.8248781

1095-9203

Zohreh Farahbakhsh, Kálmán Hideg, Wayne L. Hubbell,

Receptor Mechanisms and Signaling

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.