One of the key features of the plasma membrane is the asymmetrical distribution of phospholipids across it. Especially, phosphatidylserine (PS) exclusively locates on its inner leaflet. Thus, the exposure of PS on the surface of cells could function as a signal initiating various cellular processes such as phagocytosis of apoptotic cells called efferocytosis, blood clotting, muscle formation, and viral entry. Indeed, PS on apoptotic cells stimulates phagocytes to engulf them and functions as an essential ligand for efferocytosis. Due to the importance of PS in efferocytosis, the existence of the PS receptor had been conceived. However, the PS receptor had not been revealed for a long time. Thus, the first identification of the PS receptor was significant excitement. Tim-4, a member of the T cell immunoglobulin and mucin domain containing family of genes, was one of PS receptors which first identified and received the greatest attention due to its expression in macrophages and relevance to autoimmune and allergic diseases. This review will serve to provide a comprehensive overview of Tim proteins as PS receptors.

质膜的关键特征之一是磷脂在整个膜上的不对称分布。特别是，磷脂酰丝氨酸（PS）仅位于其内部小叶上。因此，PS在细胞表面的暴露可以作为启动各种细胞过程的信号，例如凋亡细胞的吞噬作用（称为胞吞作用），血液凝结，肌肉形成和病毒进入。实际上，凋亡细胞上的PS会刺激吞噬细胞吞噬吞噬细胞，并充当胞吐作用的基本配体。由于PS在胞吐作用中的重要性，已经设想了PS受体的存在。然而，PS受体很长时间没有被发现。因此，PS受体的首次鉴定是令人兴奋的。蒂姆4，T细胞免疫球蛋白和粘蛋白结构域基因家族的成员之一是PS受体之一，由于其在巨噬细胞中的表达以及与自身免疫性疾病和过敏性疾病的相关性，因此最先被发现并受到了最大的关注。这篇综述将提供Tim蛋白作为PS受体的全面概述。