Structure‐function relationships of cation translocation by Ca2+‐ and Na+,K+‐ATPases studied by site‐directed mutagenesis

FEBS Letters

Anderssen, Jens Peter¹  Vilsen, Bente¹ 

[1] Danish Biomembrane Research Centre, Institute of Physiology, University of Aarhus, Ole Worms Allé 160, Dk-8000 Aarhus C, Denmark

关键词: P-type ATPase;    Calcium;    Sodium;    Potassium;    Ion pump;    Ion channel;    CrATP;    βγ-bidentate chromium(III) complex of ATP;    K 0.5;    concentration giving half maximal activation;    M1-M10;    putative transmembrane segments numbered from the NH2-terminal end of the peptide;    wild type;    the non-mutated form of the exogenous enzyme expressed following transfection;   

DOI  :  10.1016/0014-5793(95)00019-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Site-directed mutagenesis studies of the sarcoplasmic reticulum Ca²⁺-ATPase have pinpointed five amino acid residues that are essential to Ca²⁺ occlusion, and these residues have been assigned to different parts of a Ca²⁺ binding pocket with channel-like structure. Three of the homologous Na⁺,K⁺-ATPase residues have been shown to be important for binding of cytoplasmic Na⁺ at transport sites. In addition, three of the above mentioned Ca²⁺-ATPase residues appear to participate in the countertransport of H⁺, and two of the Na⁺,K⁺-ATPase residues to participate in the countertransport of K⁺. Residues involved in energy transducing conformational changes have also been identified by mutagenesis. In the Ca²⁺-ATPase, ATP hydrolysis is uncoupled from Ca²⁺ transport following mutation of a tyrosine residue located at the top of transmembrane segment M5. This tyrosine, present also in the Na⁺,K⁺-ATPase, may play a critical role in closing the gate to a transmembrane channel.

【 授权许可】

Unknown