Figure 2. Metarhodopsin III formation can simulate rhodopsin diffusion. The series of spectra was recorded with the measuring beam placed at ROS center, in darkness and at various intervals after 1-s full-field bleach. The curves are color-coded to facilitate tracing individual spectra. Peak of Meta III at approximately 480 nm reaches its maximum at 100 s postbleach. Though λ_max of Meta III is blue-shifted compared to rhodopsin, Meta III spectrum has a long-wave tail that runs virtually parallel to the spectrum of rhodopsin. Therefore, there is no wavelength for diffusion measurements where Meta III contribution can be neglected. Recordings are made in standard Ringer solution at pH 7.5. Spectra represent average of seven cells.