DISTRIBUTION OF GUANYLATE-CYCLASE WITHIN PHOTORECEPTOR OUTER SEGMENTS

Guanylate cyclases play an essential role in the recovery of vertebrat e photoreceptor cells after light activation. Here, we have investigat ed how one such guanylate cyclase, RetGC-1, is distributed within ligh t- and dark-adapted rod photoreceptor cells. Guanylate cyclase activit y partitioned with the photoreceptor outer segment (OS) cytoskeleton i n a light-sensitive manner. RetGC-1 was found to bind actin filaments in actin blot overlays, suggesting a mechanism for its association wit h the OS cytoskeleton. In retinal sections, this enzyme was immunodete cted only in the OSs, where it appeared to be distributed throughout t he disk membranes.