Structure-function Relationships of Cation Translocation by Ca(2+)- And Na+, K(+)-ATPases Studied by Site-Directed Mutagenesis

FEBS Lett. 1995 Feb 13;359(2-3):101-6. doi: 10.1016/0014-5793(95)00019-6.

Abstract

Site-directed mutagenesis studies of the sarcoplasmic reticulum Ca(2+)-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 Ca(2+)-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 Ca(2+)-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.

Publication types

  • Review

MeSH terms

  • Amino Acid Sequence
  • Calcium / metabolism*
  • Ion Transport
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Sodium-Potassium-Exchanging ATPase / chemistry
  • Sodium-Potassium-Exchanging ATPase / genetics
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Structure-Activity Relationship

Substances

  • Sodium-Potassium-Exchanging ATPase
  • Calcium