Guanylate Cyclase of Retinal Rod Outer Segment
Guanylate cyclase activity was studied in the rod outer segments of the toad retina. The enzyme becomes sensitive to calcium ions after illumination, showing an enhancement of its activity when Ca2+ concentration is lowered from 10−5 M to less than 10−8 M. A possible pathway of cyclase activation by light was also investigated. When Zaprinast was used as inhibitor of phosphodiesterase, the light-activation of cyclase and of phosphodiesterase were simultaneously suppressed, suggesting a coupling of the two antagonist enzymes.
KeywordsCyclase Activity Guanylate Cyclase Dark Light Guanylate Cyclase Activity Toad Retina
Unable to display preview. Download preview PDF.