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From Proteopedia

Revision as of 16:31, 10 April 2015

Aquaporin The water channel of the cell

This is a membrane proteins that control the amount of water that travels in and out of the cell. It was thought that water molecule just leaked through the phospholipid bilayer. Aquaporins allow water to flow rapidly to the inside of cell then it would by crossing the bilayer. This protein is highly selective to water molecules , preventing the passage of ions and other solutes.There are multiple types of aquaporins that can allow the transport of other molecules such as glycerol,CO2, ammonia and urea by aquaglyceroporin. It depends on the size of the pore; aquaporin 3 channel has a pore width of 8-10 Ångströms and allows the passage of hydrophilic molecules ranging between 150-200 Da. Aquaporins water channel are impermeable to protons and other charged species Water molecules traverse through the pore of the channel in single file. The presence of water channels increases membrane permeability to water.

Structure

Aquaporin is a six transmembrane alpha helices; the amino and craboxyl terminal are located at the cytoplasm. The protein is divided into two halves of similar sequence. Aquaporin is a tetramer, each monomer is able to channel water.

The location of Aquaporin is usually found in the kindney, eye and plants.

Cite: http://www.ks.uiuc.edu/Research/aquaporins/

Alpha Helices,  Beta Strands ,  Loops , Turns.