Brisson A, Mosser G, Huber R
CNRS Unité 184 de Biologie Moléculaire et de Génie Génétique, INSERM Institut de Chimie Biologique, Faculté de Médecine, Strasbourg, France.
J Mol Biol. 1991 Jul 20;220(2):199-203. doi: 10.1016/0022-2836(91)90002-n.
Annexins are a family of water-soluble proteins that bind to membranes in a calcium-dependent manner. Some members have been shown to exhibit voltage-dependent calcium channel activity, a property characteristic of integral membrane proteins. The structures of human annexin V in crystals obtained from aqueous solution and in two-dimensional crystals when bound to phospholipid layers have been determined by X-ray and electron crystallography, respectively. They are compared here. Both structures show close correspondence, suggesting that annexins attach to phospholipid membranes without substantial structural change. These observations, together with biochemical data, lead to the conclusion that annexin V interacts with phospholipid membranes with its convex face. We propose that binding is mediated by direct interaction between the phosphoryl headgroups and the calcium bound to polypeptide loops protruding from the convex face. The membrane area covered by annexin may thus become disordered and permeable allowing calcium flux through the membrane and the central channel-like structure found in annexin molecules.
膜联蛋白是一类水溶性蛋白质家族，它们以钙依赖的方式与膜结合。一些成员已被证明具有电压依赖性钙通道活性，这是整合膜蛋白的一个特性。分别通过X射线晶体学和电子晶体学确定了从水溶液中获得的晶体形式以及与磷脂层结合时二维晶体形式的人膜联蛋白V的结构。在此对它们进行比较。两种结构显示出密切的对应关系，表明膜联蛋白附着于磷脂膜时没有实质性的结构变化。这些观察结果与生化数据一起得出结论，即膜联蛋白V以其凸面与磷脂膜相互作用。我们提出，结合是由磷酰头部基团与结合到从凸面突出的多肽环上的钙之间的直接相互作用介导的。因此，膜联蛋白覆盖的膜区域可能会变得无序且具有通透性，从而允许钙通过膜以及膜联蛋白分子中发现的中央通道样结构流动。
