Peter Agre Peter Agre is Professor of Biological Chemistry and Professor of Medicine at Johns Hopkins School of Medicine in Baltimore, USA.
Water channels: The cell leaks like a sieve
How does water actually pass through the cell membrane? The answer eluded researchers for over a hundred years. It was Peter Agre who finally unravelled the secret. By a happy chance he found the protein that is needed for water to pass in and out. He had discovered the elusive water channel.
The decisive experiment
The world’s most efficient recycling plant
In twenty-four hours, the human kidney produces about 170 litres of primary urine. Fortunately most of this is recovered thanks to a series of cunning mechanisms so that finally only about one litre of urine leaves the body during this time. This recycling machinery consists chiefly of aquaporins – tens of thousands of millions in a single kidney.
In 1992 Peter Agre conducted an elegant experiment in which he kept, in water, frog oocytes into which he had introduced a membrane protein called CHIP28. After some minutes the cells containing the protein had swollen up, while the others were unaffected. Obviously, the CHIP28 protein was needed for the cell to be able to let water in – the first water channel was discovered. Agre renamed the protein aquaporin, “water pore”. Eight years later and jointly with other research teams he presented the first high-resolution images of the three-dimensional structure of this protein.
Peter Agre’s decisive experiment showed that only those cells that contain aquaporin (to the right in the pictures) can absorb water and swell up.