1j4n
From Proteopedia
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Crystal Structure of the AQP1 water channel
Overview
Water channels facilitate the rapid transport of water across cell, membranes in response to osmotic gradients. These channels are believed to, be involved in many physiological processes that include renal water, conservation, neuro-homeostasis, digestion, regulation of body temperature, and reproduction. Members of the water channel superfamily have been found, in a range of cell types from bacteria to human. In mammals, there are, currently 10 families of water channels, referred to as aquaporins (AQP):, AQP0-AQP9. Here we report the structure of the aquaporin 1 (AQP1) water, channel to 2.2 A resolution. The channel consists of three topological, elements, an extracellular and a cytoplasmic vestibule connected by an, extended narrow pore or selectivity filter. Within the selectivity filter, four bound waters are localized along three hydrophilic nodes, which, punctuate an otherwise extremely hydrophobic pore segment. This unusual, combination of a long hydrophobic pore and a minimal number of solute, binding sites facilitates rapid water transport. Residues of the, constriction region, in particular histidine 182, which is conserved among, all known water-specific channels, are critical in establishing water, specificity. Our analysis of the AQP1 pore also indicates that the, transport of protons through this channel is highly energetically, unfavourable.
About this Structure
1J4N is a Single protein structure of sequence from Bos taurus with BNG as ligand. Full crystallographic information is available from OCA.
Reference
Structural basis of water-specific transport through the AQP1 water channel., Sui H, Han BG, Lee JK, Walian P, Jap BK, Nature. 2001 Dec 20-27;414(6866):872-8. PMID:11780053
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