The molecular mechanism for the spectral shifts between vertebrate ultraviolet- and violet-sensitive cone visual pigments

The molecular mechanism for the spectral shifts between vertebrate ultraviolet- and violet-sensitive cone visual pigments

The short-wave-sensitive (SWS) visual pigments of vertebrate cone photoreceptors are divided into two classes on the basis of molecular identity, SWS1 and SWS2. Only the SWS1 class are present in mammals. The SWS1 pigments can be further subdivided into violet-sensitive (VS), with lambda(max) (the p...

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Bibliographic Details
Published in:Biochemical journal 2002-10, Vol.367 (Pt 1), p.129-135
Main Authors: Cowing, Jill A, Poopalasundaram, Subathra, Wilkie, Susan E, Robinson, Phyllis R, Bowmaker, James K, Hunt, David M
Format: Article
Language:eng
Subjects:
Animals
Biological Evolution
Cattle
DNA, Complementary - metabolism
Genetic Vectors
Goldfish
Models, Molecular
Mutagenesis, Site-Directed
Mutation
Phenylalanine - chemistry
Phylogeny
Protein Conformation
Retinal Pigments - chemistry
Retinal Pigments - physiology
Rod Opsins - chemistry
Sequence Homology, Amino Acid
Spectrophotometry
Swine
Tyrosine - chemistry
Ultraviolet Rays
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Summary:The short-wave-sensitive (SWS) visual pigments of vertebrate cone photoreceptors are divided into two classes on the basis of molecular identity, SWS1 and SWS2. Only the SWS1 class are present in mammals. The SWS1 pigments can be further subdivided into violet-sensitive (VS), with lambda(max) (the peak of maximal absorbance) values generally between 400 and 430 nm, and ultraviolet-sensitive (UVS), with a lambda(max)Tyr substitution is sufficient by itself to shift the lambda(max) of the goldfish pigment from a wild-type value of 360 nm to around 420 nm, and the reverse substitution of Tyr-86-Phe into bovine VS opsin produces a similar shift in the opposite direction. The substitution of this single amino acid is sufficient to account therefore for the evolution of bovine and porcine VS pigments. The replacement of Phe with polar Tyr at site 86 is consistent with the stabilization of Schiff-base protonation in VS pigments and the absence of protonation in UVS pigments.
ISSN:0264-6021
1470-8728