Haines T H
Department of Chemistry, City College, City University of New York, NY 10031.
FEBS Lett. 1994 Jun 6;346(1):115-22. doi: 10.1016/0014-5793(94)00470-6.
The rate of the lateral diffusion of straight-chain phospholipids predicts the rate of water diffusion through bilayers. A new model of lipid dynamics integrates these processes. Substances such as cholesterol that reduce water diffusion proportionally reduce lateral diffusion. The model yields a number of predictions about the dynamics of the lipids at the Tm and suggests different mechanisms for how water diffuses across bilayers of other-than-straight-chain lipids, and how proteins bind to membranes. A second recent development in water transport across biological membranes is the discovery of a ubiquitous family of water transport proteins that facilitate large-volume water translocation. Like water diffusion through lipid bilayers, water transport by these proteins is directed by osmosis and is therefore under the control of ATP and ion pumps. The presence of water transport proteins in membranes is often regulated by hormones.
直链磷脂的侧向扩散速率预示着水通过双层膜的扩散速率。一种新的脂质动力学模型整合了这些过程。像胆固醇这样降低水扩散的物质会按比例降低侧向扩散。该模型对脂质在熔点时的动力学做出了一些预测，并提出了不同的机制，以解释水如何穿过非直链脂质双层膜，以及蛋白质如何与膜结合。生物膜水运输领域最近的第二项进展是发现了一个普遍存在的水运输蛋白家族，该家族促进大量水的转运。与水通过脂质双层膜的扩散一样，这些蛋白质介导的水运输受渗透作用的引导，因此受ATP和离子泵的控制。膜中存在的水运输蛋白通常受激素调节。
