Cone visual pigments are present in gecko rod cells

Daisuke Kojima, Toshiyuki Okano, Yoshitaka Fukada, Yoshinori Shichida, Tôru Yoshizawa*, Thomas G. Ebrey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

107 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)6841-6845
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number15
Publication statusPublished - 1992
Externally publishedYes


  • Rod and cone
  • Transmutation theory
  • cDNA cloning

ASJC Scopus subject areas

  • General


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