Breaking the covalent bond - A pigment property that contributes to desensitization in cones

Vladimir J. Kefalov; Maureen E. Estevez; Massahiro Kono; Patrice W. Goletz; Rosalie K. Crouch; M. Carter Cornwall; King Wai Yau

doi:10.1016/j.neuron.2005.05.009

Breaking the covalent bond - A pigment property that contributes to desensitization in cones

Vladimir J. Kefalov
, Maureen E. Estevez
, Massahiro Kono
, Patrice W. Goletz
, Rosalie K. Crouch
, M. Carter Cornwall
, King Wai Yau

School of Medicine

Research output: Contribution to journal › Article › peer-review

90 Scopus citations

Abstract

Retinal rod and cone pigments consist of an apoprotein, opsin, covalently linked to a chromophore, 11-cis retinal. Here we demonstrate that the formation of the covalent bond between opsin and 11-cis retinal is reversible in darkness in amphibian red cones, but essentially irreversible in red rods. This dissociation, apparently a general property of cone pigments, results in a surprisingly large amount of free opsin - about 10% of total opsin - in dark-adapted red cones. We attribute this significant level of free opsin to the low concentration of intracellular free 11-cis retinal, estimated to be only a tiny fraction (∼0.1 %) of the pigment content in red cones. With its constitutive transducin-stimulating activity, the free cone opsin produces an ∼2-fold desensitization in red cones, equivalent to that produced by a steady light causing 500 photoisomerizations s^-1. Cone pigment dissociation therefore contributes to the sensitivity difference between rods and cones.

Original language	English (US)
Pages (from-to)	879-890
Number of pages	12
Journal	Neuron
Volume	46
Issue number	6
DOIs	https://doi.org/10.1016/j.neuron.2005.05.009
State	Published - Jun 16 2005

ASJC Scopus subject areas

General Neuroscience

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10.1016/j.neuron.2005.05.009

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@article{1579747ed4c545ff8832694e2c564927,

title = "Breaking the covalent bond - A pigment property that contributes to desensitization in cones",

abstract = "Retinal rod and cone pigments consist of an apoprotein, opsin, covalently linked to a chromophore, 11-cis retinal. Here we demonstrate that the formation of the covalent bond between opsin and 11-cis retinal is reversible in darkness in amphibian red cones, but essentially irreversible in red rods. This dissociation, apparently a general property of cone pigments, results in a surprisingly large amount of free opsin - about 10\% of total opsin - in dark-adapted red cones. We attribute this significant level of free opsin to the low concentration of intracellular free 11-cis retinal, estimated to be only a tiny fraction (∼0.1 \%) of the pigment content in red cones. With its constitutive transducin-stimulating activity, the free cone opsin produces an ∼2-fold desensitization in red cones, equivalent to that produced by a steady light causing 500 photoisomerizations s-1. Cone pigment dissociation therefore contributes to the sensitivity difference between rods and cones.",

author = "Kefalov, \{Vladimir J.\} and Estevez, \{Maureen E.\} and Massahiro Kono and Goletz, \{Patrice W.\} and Crouch, \{Rosalie K.\} and Cornwall, \{M. Carter\} and Yau, \{King Wai\}",

note = "Funding Information: This paper is dedicated to the memory of Edward (Ted) MacNichol, whose apparatus was used for some of the microspectrophotometric (MSP) experiments. We thank Dr. David Cameron for help in the collection and analysis of some early MSP data and Dr. Clint Makino for the use of his MSP instrument, Dr. Barbara Wiggert for a generous gift of IRBP, and Dr. John Crabb for the gift of the CRALBP expression vector. Members of the Yau laboratory have provided invaluable comments on the work and manuscript. Supported by NIH EY 06837 and the Ruth and Milton Steinbach Fund (K.-W.Y.), EY 01157 (M.C.C.), EY 04939 (R.K.C.), EY 13748 (M.K.), and an unrestricted grant to the Department of Ophthalmology, MUSC from Research to Prevent Blindness.",

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AU - Kefalov, Vladimir J.

AU - Estevez, Maureen E.

AU - Kono, Massahiro

AU - Goletz, Patrice W.

AU - Crouch, Rosalie K.

AU - Cornwall, M. Carter

AU - Yau, King Wai

N1 - Funding Information: This paper is dedicated to the memory of Edward (Ted) MacNichol, whose apparatus was used for some of the microspectrophotometric (MSP) experiments. We thank Dr. David Cameron for help in the collection and analysis of some early MSP data and Dr. Clint Makino for the use of his MSP instrument, Dr. Barbara Wiggert for a generous gift of IRBP, and Dr. John Crabb for the gift of the CRALBP expression vector. Members of the Yau laboratory have provided invaluable comments on the work and manuscript. Supported by NIH EY 06837 and the Ruth and Milton Steinbach Fund (K.-W.Y.), EY 01157 (M.C.C.), EY 04939 (R.K.C.), EY 13748 (M.K.), and an unrestricted grant to the Department of Ophthalmology, MUSC from Research to Prevent Blindness.

PY - 2005/6/16

Y1 - 2005/6/16

N2 - Retinal rod and cone pigments consist of an apoprotein, opsin, covalently linked to a chromophore, 11-cis retinal. Here we demonstrate that the formation of the covalent bond between opsin and 11-cis retinal is reversible in darkness in amphibian red cones, but essentially irreversible in red rods. This dissociation, apparently a general property of cone pigments, results in a surprisingly large amount of free opsin - about 10% of total opsin - in dark-adapted red cones. We attribute this significant level of free opsin to the low concentration of intracellular free 11-cis retinal, estimated to be only a tiny fraction (∼0.1 %) of the pigment content in red cones. With its constitutive transducin-stimulating activity, the free cone opsin produces an ∼2-fold desensitization in red cones, equivalent to that produced by a steady light causing 500 photoisomerizations s-1. Cone pigment dissociation therefore contributes to the sensitivity difference between rods and cones.

AB - Retinal rod and cone pigments consist of an apoprotein, opsin, covalently linked to a chromophore, 11-cis retinal. Here we demonstrate that the formation of the covalent bond between opsin and 11-cis retinal is reversible in darkness in amphibian red cones, but essentially irreversible in red rods. This dissociation, apparently a general property of cone pigments, results in a surprisingly large amount of free opsin - about 10% of total opsin - in dark-adapted red cones. We attribute this significant level of free opsin to the low concentration of intracellular free 11-cis retinal, estimated to be only a tiny fraction (∼0.1 %) of the pigment content in red cones. With its constitutive transducin-stimulating activity, the free cone opsin produces an ∼2-fold desensitization in red cones, equivalent to that produced by a steady light causing 500 photoisomerizations s-1. Cone pigment dissociation therefore contributes to the sensitivity difference between rods and cones.

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JO - Neuron

JF - Neuron

IS - 6

ER -

Breaking the covalent bond - A pigment property that contributes to desensitization in cones

Abstract

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