How Cells Hydrate: Aquaporin Channels
In the 1980s, Peter Agre, M.D, Professor of Biological Chemistry at Johns Hopkins School of Medicine, and his colleagues were searching for proteins that are part of the Rh factor. They soon discovered copious amounts of a much smaller unknown protein. Within a year, this protein was proven to be biology’s elusive cellular regulator of water transport.
They named these tiny protein channels aquaporins, and discovered that only single water molecules can pass through aquaporins. The rate of flow was calculated in the hundreds of millions of molecules per second, per channel. With hundreds, if not thousands of channels per cell, this equates to hundreds of billions of water molecules per second, per cell. These numbers provide a vivid perspective of the size of a water molecule and the amazing complexity of our cells.
During the same period, Roderick MacKinnon, M.D., biophysicist, x-ray crystallographer, and professor at Rockefeller University, was also working with human cells. He documented how a class of proteins helps to generate nerve impulses. These proteins, called ion channels, are tiny pores that stud the surface of all of our cells. These channels allow the passage of mineral ions into the cell. Rapid-fire opening and closing of these channels releases ions, moving electrical impulses, from the brain to their destination in the body. This proves that water molecules and mineral ions have separate pathways into the cells.
Fifteen years after their discoveries, an enormous body of work by hundreds of medical researchers in universities around the world has not only validated these findings but has shown that virtually all life on this planet operates on the same principals of hydration, oxygenation, detoxification, and balancing the acid-alkaline ratio of their respective cells, i.e. water molecules must pass single-file through aquaporin channels, and water molecules and mineral ions have separate pathways into the cells.
In 2003, Dr. Agre and Dr. MacKinnon were jointly awarded the Nobel Prize in chemistry for their respective contributions.