Regulation of cyclic GMP binding to retinal rod membranes by calcium |
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| Authors: | A Caretta A Cavaggioni R Grimaldi R T Sorbi |
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| Institution: | Istituto di Fisiologia Umana, Università di Parma, Italy. |
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| Abstract: | The apparently cooperative binding of 8-(5-thioacetamidofluorescein)-cGMP (SAF-cGMP) to cGMP-binding sites of the rod outer segments is regulated by Ca2+ in the 0.1-1 microM activity range. High Ca2+ reduces, and low Ca2+ increases the affinity of SAF-cGMP binding. This regulation involves only intrinsic membrane components. It is proposed that an allosteric regulation of cGMP binding by Ca2+ can contribute to photoreceptor potential adaptation. |
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