Aquaporin

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{{STRUCTURE_1h6i| PDB=1h6i | SIZE=400| SCENE= |right|CAPTION=Human aquaporin 1, [[1h6i]] }}
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{{STRUCTURE_1h6i| PDB=1h6i | SIZE=350| SCENE= |right|CAPTION=Human aquaporin 1, [[1h6i]] }}
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[[Image:3gd8.png|left|200px|thumb|Crystal Structure of Human Aquaporin 4, [[3gd8]]]]
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== Function ==
== Function ==

Revision as of 10:55, 2 December 2015

Template:STRUCTURE 1h6i

Contents

Function

Aquaporins are channel producing proteins which regulate the flow of water across the cell membrane. The image on the left shows the protein, 6 molecules of glycerol and one of beta-octylglucoside.

  • Aquaporin-0 functions as water channel in lens fibers.
  • Aquaporin-1 see details in Aquaporin-1.
  • Aquaporin-2 function is to reabsorb water from urine in the kidney.
  • Aquaporin-3 function is to promote glycerol permeability across cell membrane.
  • Aquaporin-4 regulates water balance in the central nervous system.
  • Aquaporin-5 is implicated in the forming of saliva, tears and pulmonary secretions.
  • Aquaporin-Z is a major water channel in bacteria.
  • Aquaglycerolporin (GLpf) is a water channel which can transport glycerol, polyalcohols, urea and other small solutes.

Disease

Mutations in aquaporin-2 cause diabitis insipidus. Mutations in aquaporin-0 in mice cause congenital cataracts. Aquaporin-4 is the primary autoimmune target of neuromyelitis optica.

Structural highlights

Aquaporins are made of α-helix bundles. The water transporting channel contains 2 restriction sites conferring an hourglass model to the channel. Two NPA motifs from opposite surfaces form one restriction. Another restriction is formed by a cluster of aromatic/arginine side chains which serves to weaken the hydrogen bonding between water molecules.

3D Structures of Aquaporin

Updated on 02-December-2015


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