Identification of Asp804 and Asp808 as Na+ and K+ coordinating residues in α‐subunit of renal Na,K‐ATPase
- 3 January 1997
- journal article
- Published by Wiley in FEBS Letters
- Vol. 400 (2) , 206-210
- https://doi.org/10.1016/s0014-5793(96)01381-6
Abstract
Mutations to Asp804 and Asp808 in the α-subunit almost abolish Na,K-ATPase activity, but high-affinity binding of [3H]ATP or [3H]ouabain at equilibrium and E1–E2 transitions are preserved. Titration of K+-ion displacement of [3H]ATP or [3H]ouabain shows that the mutations interfere with occlusion of K+ in the E2[2K] conformation. Reduced phosphorylation levels or affinities for Na+ in presence of oligomycin indicate that Asp804 and Asp808 also contribute to coordination of Na+ in the E1P[3Na] form. Demonstration of alternate interactions of Na+ or K+ with Asp804 and Asp808 support the notion of cation binding in a ping-pong sequence in catalytic models of Na,K-pumpingKeywords
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