Question

Describe the structure of AQP1, and explain how aquaporins (AQPs) are able to transport water, while restricting proton hopping.

Answer 1

Structure of Aquaporin-1 (AQP1)

An AQP1 monomer unit consists of six tilted transmembrane, alpha helical domains with both carboxylic and amino terminals on the cytoplasmic side.The α-helices and two internal α-helices are oriented in the form of a barrel. The α-helices thread through the membrane so as to hold both the N- and the C-terminus to the inner cytoplasm.Dimensially they have a length of 18Å ,diameter of 4 Å and 25° bend.

   

Aquaporins selectively conduct water molecules in and out of the cell restricting proton hopping.They prevent the passage of ions and other solutes.are small integral membrane proteins residing in the plasma membrane.They are water-selective and transport glycerol. They form bidirectional osmotic water transport channels across the plasma membrane and transport water across cell membranes in accordance to osmotic gradients created by active solute transport.