Mechanism of Spectral Tuning in the Dolphin Visual Pigments
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- 作者：Jeffry I. Fasick and Phyllis R. Robinson
- 刊名：Biochemistry
- 出版年：1998
- 出版时间：January 13, 1998
- 年：1998
- 卷：37
- 期：2
- 页码：433 - 438
- 全文大小：61K
- 年卷期：v.37,no.2(January 13, 1998)
- ISSN：1520-4995
文摘
The absorption maxima of both rod and cone visual pigments of thebottlenose dolphin (Tursiopstruncatus) are blue-shifted relative to those of terrestrialmammals. A comparison of the sequence of thedolphin rod photopigment gene with that of the bovine rod suggeststhat, of the 28 nonidentical aminoacids, three amino acid substitutions at positions 83, 292, and 299 inthe dolphin rod pigment are responsiblefor the 10 nm blue shift in absorption maxima. A similarcomparison of the dolphin long-wavelengthsensitive (LWS) cone photopigment gene with those of the human LWScones suggests that a singlesubstitution at position 292 (using the convention of rhodopsinnumbering) in the dolphin LWS conepigment results in a blue shift in absorption maxima. Amutagenesis study reveals that the combinationof the three dolphin specific substitutions in the bovine rod pigment(83D to 83N, 292A to292S, and 299A to299S) causes a blue shift from the wild-type
max of 499 nm to 489 nm. The single substitution inthedolphin LWS cone pigment (292S to 292A) causesa red shift from the wild-type max of 524 nm to 552nm.The interactions of the three amino acids identified in the rodpigment with the chromophore may be ageneral mechanism for blue shifting in rod visual pigments.Furthermore, the single substitution in thedolphin LWS opsin gene is a novel mechanism of wavelength modulation inmammalian LWS pigments.
max of 499 nm to 489 nm. The single substitution inthedolphin LWS cone pigment (292S to 292A) causesa red shift from the wild-type max of 524 nm to 552nm.The interactions of the three amino acids identified in the rodpigment with the chromophore may be ageneral mechanism for blue shifting in rod visual pigments.Furthermore, the single substitution in thedolphin LWS opsin gene is a novel mechanism of wavelength modulation inmammalian LWS pigments.