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Do H + ions obscure electrogenic Na + and K + binding in the E 1 state of the Na,K‐ATPase?
Author(s) -
Apell Hans-Jürgen,
Diller Anna
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)03675-x
Subject(s) - chemistry , ion , crystallography , atpase , binding site , ion transporter , transmembrane protein , biophysics , enzyme , biochemistry , biology , receptor , organic chemistry
In contrast to other P‐type ATPases, the Na,K‐ATPase binding and release of ions on the cytoplasmic side, to the state called E 1 , is not electrogenic with the exception of the third Na + . Since the high‐resolution structure of the closely related SR Ca‐ATPase in state E 1 revealed the ion‐binding sites deep inside the transmembrane part of the protein, the missing electrogenicity in state E 1 can be explained by an obscuring counter‐movement of H + ions. Evidence for such a mechanism is presented by analysis of pH effects on Na + and K + binding and by electrogenic H + movements in the E 1 conformation of the Na,K‐ATPase.