A Ca++-Dependent and -Selective Ionophore as Part of the Ca++ + Mg++-Dependent Adenosinetriphosphatase of Sarcoplasmic Reticulum

AUTOR(ES)

Shamoo, Adil E.

RESUMO

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.

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