The three-dimensional structure of aquaporin-1

摘要: The entry and exit of water from cells is a fundamental process life. Recognition the high permeability red blood led to proposal that specialized pores exist in plasma membrane. Expression Xenopus oocytes functional studies an erythrocyte integral membrane protein relative molecular mass 28,000, identified it as mercury-sensitive channel, aquaporin-1 (AQP1). Many related proteins, all belonging major intrinsic (MIP) family, are found throughout nature. AQP1 homotetramer containing four independent aqueous channels. When reconstituted into lipid bilayers, forms two-dimensional lattices with unit cell two tetramers opposite orientation. Here we present three-dimensional structure determined at 6A resolution by cryo-electron microscopy. Each monomer has six tilted, bilayer-spanning alpha-helices which form right-handed bundle surrounding central density. These results, together studies, provide model identifies pore molecule indicates organization tetrameric complex