Dizhoor A M, Chen C K, Olshevskaya E, Sinelnikova V V, Phillipov P, Hurley J B
Department of Biochemistry, University of Washington, Seattle 98195.
Science. 1993 Feb 5;259(5096):829-32. doi: 10.1126/science.8430337.
Recoverin, a calcium ion (Ca2+)-binding protein of vertebrate photoreceptors, binds to photoreceptor membranes when the Ca2+ concentration is greater than 1 micromolar. This interaction requires a fatty acyl residue covalently linked to the recoverin amino (NH2)-terminus. Removal of the acyl residue, either by proteolytic cleavage of the NH2-terminus or by production of nonacylated recoverin, prevented recoverin from binding to membranes. The acylated recoverin NH2-terminus could be cleaved by trypsin only when Ca2+ was bound to recoverin. These results suggest that the hydrophobic NH2-terminus is constrained in Ca(2+)-free recoverin and liberated by Ca2+ binding. The hydrophobic acyl moiety of recoverin may interact with the membrane only when recoverin binds Ca2+.
恢复蛋白是脊椎动物光感受器中的一种钙离子（Ca2+）结合蛋白，当Ca2+浓度大于1微摩尔时，它会与光感受器膜结合。这种相互作用需要一个与恢复蛋白氨基（NH2）末端共价连接的脂肪酰基残基。通过NH2末端的蛋白水解切割或通过产生非酰化的恢复蛋白去除酰基残基，可阻止恢复蛋白与膜结合。只有当Ca2+与恢复蛋白结合时，胰蛋白酶才能切割酰化的恢复蛋白NH2末端。这些结果表明，疏水的NH2末端在无Ca2+的恢复蛋白中受到限制，并通过Ca2+结合而释放。恢复蛋白的疏水酰基部分可能只有在恢复蛋白结合Ca2+时才与膜相互作用。
