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Science 14 December 1973:
Vol. 182. no. 4117, pp. 1138 - 1140
DOI: 10.1126/science.182.4117.1138
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Articles

Control of Guanylate Cyclase Activity in the Rod Outer Segment

Richard G. Pannbacker 1

1 Division of Ophthalmology and Department of Pharmacology, University of Colorado Medical Center, Denver 80220

Mammalian photoreceptors contain a guanylate cyclase which has a high specific activity and is inhibited by exposure of the rod outer segment to light. Several minutes are required for this inhibition to take effect, indicating that it is not a step in visual excitation. The activity of the enzyme is sensitive to the concentration of calcium ion in the medium, suggesting that light-induced changes in calcium distribution in the photoreceptor could control guanylate cyclase activity.

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Science. ISSN 0036-8075 (print), 1095-9203 (online)