Conserved Proline Residue at Position 189 in Cone Visual Pigments as a Determinant of Molecular Properties Different from Rhodopsins

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• 作者：Shigeki Kuwayama ; Hiroo Imai ; Takahiro Hirano ; Akihisa Terakita ; and Yoshinori Shichida
• 刊名：Biochemistry
• 出版年：2002
• 出版时间：December 24, 2002
• 年：2002
• 卷：41
• 期：51
• 页码：15245 - 15252
• 全文大小：150K
• 年卷期：v.41,no.51(December 24, 2002)
• ISSN：1520-4995

文摘

To identify the amino acid residue(s) responsible for the difference in the molecular propertiesbetween rod and cone pigments, we have prepared chicken green mutants where each of the residues(Val77, Gly144, and Pro189) completely conserved in the cone pigments was replaced with the residuein the rod pigment rhodopsin. Among the mutants, the P189I mutant showed an expression level in culturedHEK293 cells and a thermal stability higher than did the wild-type chicken green. The mutation causeda reduced decay rate of the meta II intermediate, while the mutation of the wild-type chicken rhodopsinat position 189 (I189P) resulted in an increased decay rate. The additional mutation at position 122, thepreviously reported site where the amino acid residue is one of the determinants of the meta II decay rate,converted the meta II decay rate into that observed in the wild-type chicken rhodopsin. These resultssuggest that the difference in the meta II decay rate between the chicken green and rhodopsin is due tothe difference in the amino acid residues at positions 189 and 122. The completely conserved nature ofproline at position 189 could provide a clue to the molecular evolution of the pigments.