Open AccessA Ca ++ -Dependent and -Selective Ionophore as Part of the Ca ++ + Mg ++ -Dependent Adenosinetriphosphatase of Sarcoplasmic Reticulum
Author(s) -
Adil E. Shamoo,
David H. MacLennan
Publication year - 1974
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.71.9.3522
Subject(s) - ionophore , endoplasmic reticulum , calcium , isotopes of calcium , chemistry , atpase , biophysics , biochemistry , biology , enzyme , organic chemistry
Solubilized Ca++ + Mg++ -dependent adenosinetriphosphatase (EC 3.6.1.3; ATP diphosphohydrolase) from sarcoplasmic reticulum increased bimolecular lipid membrane (oxidized cholesterol) conductance several hundred-fold. The relative conductance change and the relative permeability elicited by this material has the following sequence: Ba++ > Ca++ > Sr++ > Mg++ > Mn++ > Zn++ , Na+ , K+ , Cs+ , Li+ , and Rb+ . Zn++ and Na+ strongly inhibit the increase in Ca++ conductance obtained with solubilized Ca++ + Mg++ -dependent adenosinetriphosphatase. The Ca++ -ionophore is an integral part of the Ca++ + Mg++ -dependent adenosinetriphosphatase enzyme and may function as a Ca++ -carrier in the overall Ca++ -pump of sarcoplasmic reticulum.