STAFF PRIORITY TIME THREE DIMENSIONAL STRUCTURE OF ANNEXIN XII HEXAMER AT 2 5 E

膜联蛋白是钙和磷脂结合的家族 具有膜融合、离子通道等功能的蛋白质 形成和细胞周期调节。该化合物的晶体结构 普通九头蛇中的膜联蛋白12六聚体在2.5E分辨率下被分离 通过分子置换，使用人类膜联蛋白I单体(44% 序列同一性)作为模型。六角体形成一个凹盘 具有32个对称性，直径约100 E，厚70 E， 中央亲水通道，掩埋19%的溶剂可接近 每种单体的表面。六角体进一步稳定了六个 钙离子，由两个相反的三聚体的原子连接而成，以及六个 赖氨酸e-氨基取代结构域II钙结合中的钙离子 循环播放。六面体结构使我们提出了一种新的模型 膜联蛋白-膜相互作用(H.Luecke等，自然378,512-515 (1995))。Annexin XII的小晶体(0.05 mm x 0.15 mm x 0.15 mm) 都是在SSRL生长的，因此需要在 一个同步加速器源。的部分完整的本机数据集 在束流上收集到2.5E分辨率的冷冻晶体 SSRL的7-1号线。

Annexins are a family of calcium- and phospholipid-binding proteins whose proposed functions include membrane fusion, ion channel formation, and cell-cycle regulation. The crystal structure of the annexin XII hexamer from Hydra vulgaris was solved at 2.5 E resolution by molecular replacement, using the human annexin I monomer (44% sequence identity) as the model. The hexamer forms a concave disk with 32 symmetry, about 100 E in diameter and 70 E thick with a central hydrophilic channel, burying 19% of the solvent-accessible surface of each monomer. The hexamer is further stabilized by six calcium ions, liganded by atoms from the two opposing trimers, and six lysine e-amino groups replacing Ca2+ in the domain II calcium-binding loop. The hexameric structure has led us to propose a new model of annexin-membrane interaction (H. Luecke et al., Nature 378, 512-515 (1995)). Small crystals (0.05 mm x 0.15 mm x 0.15 mm) of annexin XII were grown at SSRL, necessitating X-ray diffraction data collection at a synchrotron source. A partially complete native data set of a frozen crystal diffracting to 2.5 E resolution was collected at beam line 7-1 at SSRL.