Identification of Asp804 and Asp808 as Na+ and K+ coordinating residues in α‐subunit of renal Na,K‐ATPase

FEBS Letters

Jorgensen, Peter L¹  Rasmussen, Jakob H¹  Nielsen, Jesper M¹  Pedersen, Per Amstrup¹ 

[1] Biomembrane Research Centre, August Krogh Institute, Copenhagen University, 2100 Copenhagen OE, Denmark

关键词: Na;    K-ATPase;    Ouabain;    Sodium;    Potassium;    Mutagenesis;    Yeast expression;   

DOI  :  10.1016/S0014-5793(96)01381-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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-pumping.

【 授权许可】

Unknown