Stroud Robert M, Miercke Larry J W, O'Connell Joseph, Khademi Shahram, Lee John K, Remis Jonathan, Harries William, Robles Yaneth, Akhavan David
Department of Biochemistry & Biophysics, School of Medicine, 600 16th Street, University of California San Francisco, CA 94143-2240, USA.
Curr Opin Struct Biol. 2003 Aug;13(4):424-31. doi: 10.1016/s0959-440x(03)00114-3.
The aqua (glycero) porins conduct water (and glycerol) across cell membranes. The structure of these channels reveals a tripathic channel that supports a hydrophobic surface and, opposite to this, a line of eight hydrogen-bond acceptors and four hydrogen-bond donors. The eight carbonyls act as acceptors for water (or glycerol OH) molecules. The central water molecule in the channel is oriented to polarize hydrogen atoms outward from the center. This arrangement suggests how the structure prevents the potentially lethal conduction of protons across the membrane. The structure also suggests the mechanism behind the selectivity of aquaglyceroporins for glycerol, the basis for enantioselectivity among alditols, and the basis for the prevention of any leakage of the electrochemical gradient.
水（甘油）孔蛋白可使水（和甘油）穿过细胞膜。这些通道的结构显示出一个三通道结构，其具有一个疏水表面，与之相对的是一排八个氢键受体和四个氢键供体。八个羰基作为水（或甘油羟基）分子的受体。通道中的中心水分子定向排列，使氢原子从中心向外极化。这种排列方式表明了该结构如何防止质子跨膜进行潜在的致命传导。该结构还揭示了水甘油孔蛋白对甘油具有选择性的背后机制、糖醇对映体选择性的基础以及防止电化学梯度任何泄漏的基础。
