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© Chikashi Toyoshima, Crystal structure of the sodium pump with a bound sodium ion. The sodium-pump is a protein complex consisting of α- and β- subunits, and a FXYD protein. Three sodium ion-binding sites (I-III) are identified in the transmembrane region.

Sodium pump is a protein that uses chemical energy of ATP to transport sodium ions (Na+) out and potassium ions (K+) into the cell. It is expressed in all animal cells and maintains fundamental processes in life, notably excitation of nerve cells and contractions of heart muscle. Professor Chikashi Toyoshima’s group at the Institute of Molecular and Cellular Biosciences, the University of Tokyo, succeeded in determining the crystal structures of the sodium pump with bound sodium using SPring-8, extending their structure determination of a potassium-bound form published in 2009.

The crystal structure explains how the sodium pump selectively transports sodium out of the cell, although the concentration of potassium is much higher than that of sodium in cytoplasm. The crystal structure also shows how oligomycin, an antibiotic, blocks the action of sodium pump.

Sodium pump is the target of digitalis, a cardiotonic glycoside prescribed for more than two centuries, and is strongly associated with many diseases, such as high blood pressure, neurological disorders and cancers. The crystal structure described here provides a solid basis for developing drugs that regulate the activity of sodium pump.

(Japanese)

Paper

Ryuta Kanai, Haruo Ogawa, Bente Vilsen, Haiyan Gong, Flemming Cornelius, Chikashi Toyoshima,
“Crystal structure of a Na+-bound Na+,K+-ATPase preceding the E1P state”,
Nature　502 2013: 201-206, doi: 10.1038/nature12578.

Links

(2013). Phys.org. Retrieved November 12, 2013.

(2013). Medical News Today. Retrieved November 12, 2013.