Somerharju Pentti, Virtanen Jorma A, Cheng Kwan H, Hermansson Martin
Institute of Biomedicine, Department of Medical Biochemistry, University of Helsinki, Finland.
Biochim Biophys Acta. 2009 Jan;1788(1):12-23. doi: 10.1016/j.bbamem.2008.10.004. Epub 2008 Oct 25.
Most biological membranes are extremely complex structures consisting of hundreds of different lipid and protein molecules. According to the famous fluid-mosaic model lipids and many proteins are free to diffuse very rapidly in the plane of the membrane. While such fast diffusion implies that different membrane lipids would be laterally randomly distributed, accumulating evidence indicates that in model and natural membranes the lipid components tend to adopt regular (superlattice-like) distributions. The superlattice model, put forward based on such evidence, is intriguing because it predicts that 1) there is a limited number of allowed compositions representing local minima in membrane free energy and 2) those energy minima could provide set-points for enzymes regulating membrane lipid compositions. Furthermore, the existence of a discrete number of allowed compositions could help to maintain organelle identity in the face of rapid inter-organelle membrane traffic.
大多数生物膜是极其复杂的结构，由数百种不同的脂质和蛋白质分子组成。根据著名的流动镶嵌模型，脂质和许多蛋白质能够在膜平面内非常快速地自由扩散。虽然这种快速扩散意味着不同的膜脂会在横向随机分布，但越来越多的证据表明，在模型膜和天然膜中，脂质成分倾向于呈现规则的（类似超晶格的）分布。基于这些证据提出的超晶格模型很有趣，因为它预测：1）存在有限数量的允许组成，这些组成代表膜自由能的局部最小值；2）这些能量最小值可以为调节膜脂质组成的酶提供设定点。此外，离散数量的允许组成的存在有助于在细胞器间膜快速运输的情况下维持细胞器的特性。
