title: Photoreceptor protein s26, a cone homologue of S-modulin in frog retina.
abstract: A frog retinal protein named s26 is a 26-kDa protein found during purification of S-modulin in frog retina (Kawamura, S. (1992) Photochem. Photobiol. 56, 1173-1180). To identify its role in frog retina, first s26 was purified to nearly homogeneity with three chromatographical steps. Based on the partial amino acid sequences of the proteolysed fragments of s26, we isolated cDNAs that encode s26. The analysis of its amino acid sequence revealed that s26 is an S-modulin-like protein, while it shows higher homology to visinin. Visinin is a Ca2+-binding protein reported to be present in chicken cones, but its localization in the retina had been a subject in dispute. The present study showed that s26 is present in cone photoreceptors. The study also showed that s26 inhibits phosphorylation of rhodopsin after a light flash at high Ca2+ concentrations as S-modulin does. From these results, we concluded that s26 is a cone homologue of S-modulin. The result is consistent with the idea that each type of photoreceptors expresses each cell-type specific version of phototransduction proteins.
authors.affiliation: Department of Physiology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kawamura
authors.forename: O
authors.initials: O
authors.lastname: Kuwata
authors.forename: M
authors.initials: M
authors.lastname: Yamada
authors.forename: S
authors.initials: S
authors.lastname: Matsuda
authors.forename: O
authors.initials: O
authors.lastname: Hisatomi
authors.forename: F
authors.initials: F
authors.lastname: Tokunaga
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D051597:Hippocalcin; D008074:Lipoproteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D010766:Phosphorylation; D010802:Phylogeny; D011892:Rana catesbeiana; D051603:Recoverin; D012160:Retina / Q000378:metabolism*; D012243:Rhodopsin / Q000037:antagonists & inhibitors / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D005136:Eye Proteins; D008074:Lipoproteins; D009419:Nerve Tissue Proteins; C101179:photoreceptor protein s26, Rana catesbeiana; D051603:Recoverin; D051597:Hippocalcin; D012243:Rhodopsin