Lipid droplets (LDs), or oil bodies in plants, are specialized organelles that primarily serve as hubs of cellular metabolic energy storage and consumption. These ubiquitous cytoplasmic organelles are derived from the endoplasmic reticulum (ER) and consist of a hydrophobic neutral lipid core - mainly consisting of triglycerides and sterol esters - that is encircled by a phospholipid monolayer. The dynamic metabolic functions of the LDs are mainly executed and regulated by proteins on the monolayer surface. However, its unique architecture puts some structural constraints on the types of proteins that can associate with LDs. The lipid monolayer is decorated with either peripheral proteins or with integral membrane proteins that adopt a monotopic topology. Due to its oil-water interface, which is energetically costly, the LD surface happens to be favorable to the recruitment of many proteins involved in metabolic but also non-metabolic functions. We only started very recently to understand biophysical and biochemical principles controlling protein targeting to LDs. This review aims to summarize the most recent findings regarding this topic and proposes directions that will potentially lead to a better understanding of LD surface characteristics, as compared to bilayer membranes, and how that impacts protein-LD interactions.

脂滴 (LD) 或植物中的油体是专门的细胞器，主要作为细胞代谢能量储存和消耗的枢纽。这些无处不在的细胞质细胞器源自内质网 (ER)，由疏水性中性脂质核心组成 - 主要由甘油三酯和甾醇酯组成 - 被磷脂单层包围。LDs 的动态代谢功能主要由单层表面的蛋白质执行和调节。然而，其独特的结构对可以与 LD 相关联的蛋白质类型施加了一些结构限制。脂质单层装饰有外周蛋白或采用单一拓扑结构的完整膜蛋白。由于其油水界面，其能源成本高昂，LD 表面恰好有利于募集许多参与代谢和非代谢功能的蛋白质。我们最近才开始了解控制蛋白质靶向 LD 的生物物理和生化原理。本综述旨在总结有关该主题的最新发现，并提出可能有助于更好地理解 LD 表面特征（与双层膜相比）及其如何影响蛋白质-LD 相互作用的方向。