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Nature. 2013 Oct 10;502(7470):201-6. doi: 10.1038/nature12578. Epub 2013 Oct 2.

Crystal structure of a Na+-bound Na+,K+-ATPase preceding the E1P state.

Author information

1
Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.

Abstract

Na(+),K(+)-ATPase pumps three Na(+) ions out of cells in exchange for two K(+) taken up from the extracellular medium per ATP molecule hydrolysed, thereby establishing Na(+) and K(+) gradients across the membrane in all animal cells. These ion gradients are used in many fundamental processes, notably excitation of nerve cells. Here we describe 2.8 Å-resolution crystal structures of this ATPase from pig kidney with bound Na(+), ADP and aluminium fluoride, a stable phosphate analogue, with and without oligomycin that promotes Na(+) occlusion. These crystal structures represent a transition state preceding the phosphorylated intermediate (E1P) in which three Na(+) ions are occluded. Details of the Na(+)-binding sites show how this ATPase functions as a Na(+)-specific pump, rejecting K(+) and Ca(2+), even though its affinity for Na(+) is low (millimolar dissociation constant). A mechanism for sequential, cooperative Na(+) binding can now be formulated in atomic detail.

PMID:
24089211
DOI:
10.1038/nature12578
[Indexed for MEDLINE]

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