Stimulation of erythrocyte membrane Mg(2+)-ATPase activity by glutathione S-conjugates

Pig erythrocyte membrane Mg2+-ATPase activity was stimulated by various glutathione S-conjugates. For alkyl S-conjugates, the Km for the stimulation was lower, the more hydrophobic was the conjugate. 2,4-Dinitrophenyl-S-(N-acetyl)cysteine also stimulated the Mg2+-ATPase activity, suggesting a low specificity of the ¿glutathione S-conjugate pump¿. The Km values for the stimulation by 2,4-dinitrophenyl conjugates were lower than predictable on the basis of hydrophobicity which indicates a high affinity of the transporter for these conjugates.