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August 11, 2005

Scientist Says That Cells Direct Membrane Traffic By Channel Width

Topics: Medicine

Using steered molecular dynamics, Beckman researchers have solved a mystery that years of protein crystallography couldn't accomplish. Reporting in the August issue of Structure, they show that the main structural difference that makes an aquaporin a glycerol channel is a channel that is just a hundred-millionth of a centimeter -- an angstrom -- wider than a normal water channel. So, scientists at the University of Illinois at Urbana-Champaign say that for a glycerol molecule a measly angstrom's difference in diameter is a road-closed sign: You can't squeeze through unless you are a sleek, water-molecule-sized sports car!

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[Computer-generated simulation of two aquaporins sliced open(Photo by Kwame Ross)]

The roadway is in aquaglyceroporins - transport water plus glycerol and a few other small molecules.">aquaporins, a class of proteins that form trans-membrane channels in cell walls in all forms of life. They allow for water movement between the cell and its environment. A subfamily of aquaporins allows slightly larger molecules, such as glycerol, to pass, too. In humans, 11 aquaporins have been identified, mostly in the kidney, brain and lens of the eye. Impaired function has been implicated in a variety of diseases.

Posted by Hyscience at August 11, 2005 8:43 AM



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