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An extended Ca 2+ ‐hypothesis of visual transduction with a role for cyclic GMP
Author(s) -
Fatt P.
Publication year - 1982
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(82)81093-4
Subject(s) - rhodopsin , visual phototransduction , biophysics , cytoplasm , cyclic gmp , transduction (biophysics) , chemistry , calcium , crystallography , biochemistry , biology , enzyme , retinal , organic chemistry
A model is described having the following features: Light induces Ca 2+ release from vertebrate rod outer segments discs via pores composed of multimeric rhodopsin. Cytoplasmic Ca 2+ reversibly blocks Na + channels of the surface membrane, with the time course of development and amplitude of the response to light being influenced by restrictions on intradiscal Ca 2+ diffusion. The falling phase of response reflects a decline in cytoplasmic [Ca 2+ ] due to a Ca 2+ ‐binding protein controlled by cyclic GMP so that its binding capacity is increased by the reduction in cytoplasmic [cyclic GMP] which follows rhodopsin bleaching.