Guanylate Cyclase in Rod Outer Segments of the Toad Retina. Effect of Light and Ca2+

Overview

Journal FEBS Lett

Specialty Biochemistry

Date 1986 Jul 14

PMID 2873060

Citations 20

Authors

I M Pepe

I Panfoli

C Cugnoli

Affiliations

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Abstract

Guanylate cyclase activity was measured in disrupted rod outer segments of the toad retina. The experiments showed that cGMP is synthesized from GTP at a rate of 3 +/- 1 nmol/min per mg protein. In darkness this value is largely independent of the Ca2+ concentration, while it is enhanced by flashes of light of increasing intensity upon lowering Ca from 10-5 to 10-8 M. In view of recent observations that shortly after a flash of light calcium activity inside the photoreceptor cell decreases, it seems likely that calcium plays a regulatory role in cGMP metabolism in visual excitation.

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