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Transmission of E 1 ‐E 2 Structural Changes in Response to Na + or K + Binding in Na,K‐ATPase
Author(s) -
JORGENSEN PETER L.
Publication year - 2003
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2003.tb07135.x
Subject(s) - chemistry , crystallography , stereochemistry , binding site , conformational change , vanadate , biochemistry
A bstract : The extensive E 1 ‐E 2 conformational changes in response to Na + or K + binding in the absence of other ligands must be driven by motion of the side chains contributing to cation coordination, but the differences in structure of Na + and K + sites have not been resolved. The recent high resolution structure model of the E 2 conformation of Ca‐ATPase offers the first opportunity to examine and model the changes accompanying the adjustment of the cation sites from an E 1 form with specificity for Na + to an E 2 form with specificity for K + . The model of the E 2 form provides a remarkable fit to the data of direct Tl + or K + binding after site‐directed mutagenesis of residues Asp804 and Asp808 in M6, Glu 779, Gln776, and Ser775 in M5, and Glu327 in M4. Cytoplasmic domain movements during E 1 ↔ E 2 conformational transition can be monitored by proteolytic cleavage. Protection of the chymotrypsin‐sensitive bond at Leu266 in L2/3 and rotation of the A domain is more complete in the E 2 Mg‐vanadate‐ouabain complex than in the E 2 [2K] form.