Premium
Structure‐function relationships of cation translocation by Ca 2+ ‐ and Na + ,K + ‐ATPases studied by site‐directed mutagenesis
Author(s) -
Anderssen Jens Peter,
Vilsen Bente
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00019-6
Subject(s) - chemistry , atpase , tyrosine , endoplasmic reticulum , mutagenesis , transmembrane domain , site directed mutagenesis , atp hydrolysis , ion transporter , membrane transport , binding site , biochemistry , biophysics , stereochemistry , amino acid , crystallography , enzyme , mutation , membrane , biology , mutant , gene
Site‐directed mutagenesis studies of the sarcoplasmic reticulum Ca 2+ ‐ATPase have pinpointed five amino acid residues that are essential to Ca 2+ occlusion, and these residues have been assigned to different parts of a Ca 2+ 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 Ca 2+ 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.