Rpe65 Isomerase Associates with Membranes through an Electrostatic Interaction with Acidic Phospholipid Headgroups
作者:Quan Yuan、Joanna J. Kaylor、Anh Miu、Sara Bassilian、Julian P. Whitelegge、Gabriel H. Travis
DOI:10.1074/jbc.m109.025643
日期:2010.1
spectrometry, we show that Rpe65 is not palmitoylated nor does it appear to undergo other post-translational modifications at significant stoichiometry. Instead, we show that Rpe65 binds the acidic phospholipids, phosphatidylserine, phosphatidylglycerol, and cardiolipin, but not phosphatidic acid. No binding of Rpe65 to basic phospholipids or neutral lipids was observed. The affinity of Rpe65 to acidic phospholipids
视蛋白是脊椎动物视网膜中的光敏色素,包括 G 蛋白偶联受体和 11-顺式-视黄醛生色团。视蛋白色素对光子的吸收诱导其发色团异构化为全反式视黄醛。在短暂的活化后,视蛋白释放全反式视黄醛并对光变得不敏感。恢复对载脂蛋白视蛋白的光敏感性涉及通过称为视觉循环的酶途径将全反式视黄醛转化回 11-顺式视黄醛。该途径中的关键异构化步骤由 Rpe65 催化。Rpe65 与膜密切相关,但不包含跨膜片段。之前有人提出 Rpe65 对膜的亲和力是由于一个或多个 Cys 残基的棕榈酰化。在这项研究中,我们重新审视了这个假设。通过涉及质谱的两个独立策略,我们表明 Rpe65 没有棕榈酰化,也没有在显着的化学计量下进行其他翻译后修饰。相反,我们显示 Rpe65 结合酸性磷脂、磷脂酰丝氨酸、磷脂酰甘油和心磷脂,但不结合磷脂酸。没有观察到 Rpe65 与碱性磷脂或中性脂质的结合。Rpe65 对酸性磷脂的亲和力强烈依赖于 pH,表明