Cone visual pigments are present in gecko rod cells.
AUTOR(ES)
Kojima, D
RESUMO
The Tokay gecko (Gekko gekko), a nocturnal lizard, has two kinds of visual pigments, P467 and P521. In spite of the pure-rod morphology of the photoreceptor cells, the biochemical properties of P521 and P467 resemble those of iodopsin (the chicken red-sensitive cone visual pigment) and rhodopsin, respectively. We have found that the amino acid sequence of P521 deduced from the cDNA was very similar to that of iodopsin. In addition, P467 has the highest homology with the chicken green-sensitive cone visual pigment, although it also has a relatively high homology with rhodopsins. These results give additional strength to the transmutation theory of Walls [Walls, G. L. (1934) Am. J. Ophthalmol. 17, 892-915], who proposed that the rod-shaped photoreceptor cells of lizards have been derived from ancestral cone-like photoreceptors. Apparently amino acid sequences of visual pigments are less changeable than the morphology of the photoreceptor cells in the course of evolution.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=49600Documentos Relacionados
- The pKa of the protonated Schiff bases of gecko cone and octopus visual pigments.
- Single amino acid residue as a functional determinant of rod and cone visual pigments
- Primary structures of chicken cone visual pigments: vertebrate rhodopsins have evolved out of cone visual pigments.
- A circadian clock regulates rod and cone input to fish retinal cone horizontal cells.
- Anion sensitivity and spectral tuning of cone visual pigments in situ.