Oxysterol-binding protein (OSBP)-related proteins (ORPs) are lipid-binding proteins that are conserved from yeast to humans. They are implicated in many cellular processes including signaling, vesicular trafficking, lipid metabolism, and nonvesicular sterol transport. All ORPs contain an OSBP-related domain (ORD) that has a hydrophobic pocket that binds a single sterol. ORDs also contain additional membrane-binding surfaces, some of which bind phosphoinositides and may regulate sterol binding. Studies in yeast suggest that ORPs function as sterol transporters, perhaps in regions where organelle membranes are closely apposed. Yeast ORPs also participate in vesicular trafficking, although their role is unclear. In mammalian cells, some ORPs function as sterol sensors that regulate the assembly of protein complexes in response to changes in cholesterol levels. This review will summarize recent advances in our understanding of how ORPs bind lipids and membranes and how they function in diverse cellular processes.

中文翻译：

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氧甾醇结合蛋白的多种功能。

氧固醇结合蛋白 (OSBP) 相关蛋白 (ORP) 是从酵母到人类都保守的脂质结合蛋白。它们涉及许多细胞过程，包括信号传导、囊泡运输、脂质代谢和非囊泡甾醇转运。所有 ORP 都包含一个 OSBP 相关结构域 (ORD)，该结构域具有一个结合单一甾醇的疏水口袋。ORD 还包含额外的膜结合表面，其中一些结合磷酸肌醇并可能调节甾醇结合。在酵母中的研究表明 ORP 充当甾醇转运蛋白，可能在细胞器膜紧密并列的区域中发挥作用。酵母 ORP 也参与囊泡运输，但其作用尚不清楚。在哺乳动物细胞中，一些 ORP 充当甾醇传感器，调节蛋白质复合物的组装以响应胆固醇水平的变化。本综述将总结我们对 ORP 如何结合脂质和膜以及它们如何在不同细胞过程中发挥作用的最新进展。