Mukherjee S, Maxfield F R
Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA.
Traffic. 2000 Mar;1(3):203-11. doi: 10.1034/j.1600-0854.2000.010302.x.
Lipid compositions vary greatly among organelles, and specific sorting mechanisms are required to establish and maintain these distinct compositions. In this review, we discuss how the biophysical properties of the membrane bilayer and the chemistry of individual lipid molecules play a role in the intracellular trafficking of the lipids themselves, as well as influencing the trafficking of transmembrane proteins. The large diversity of lipid head groups and acyl chains lead to a variety of weak interactions, such as ionic and hydrogen bonding at the lipid/water interfacial region, hydrophobic interactions, and van-der-Waals interactions based on packing density. In simple model bilayers, these weak interactions can lead to large-scale phase separations, but in more complex mixtures, which mimic cell membranes, such phase separations are not observed. Nevertheless, there is growing evidence that domains (i.e., localized regions with non-random lipid compositions) exist in biological membranes, and it is likely that the formation of these domains are based on interactions similar to those that lead to phase separations in model systems. Sorting of lipids appears to be based in part on the inclusion or exclusion of certain types of lipids in vesicles or tubules as they bud from membrane organelles.
细胞器之间的脂质组成差异很大，需要特定的分选机制来建立和维持这些不同的组成。在本综述中，我们讨论了膜双层的生物物理特性和单个脂质分子的化学性质如何在脂质自身的细胞内运输中发挥作用，以及如何影响跨膜蛋白的运输。脂质头部基团和酰基链的巨大多样性导致了多种弱相互作用，如脂质/水界面区域的离子键和氢键、疏水相互作用以及基于堆积密度的范德华相互作用。在简单的模型双层膜中，这些弱相互作用可导致大规模的相分离，但在模拟细胞膜的更复杂混合物中，未观察到此类相分离。然而，越来越多的证据表明生物膜中存在结构域（即具有非随机脂质组成的局部区域），并且这些结构域的形成可能基于与导致模型系统中相分离的相互作用类似的相互作用。脂质的分选似乎部分基于囊泡或小管从膜细胞器出芽时某些类型脂质的包含或排除。
