The site of action of La3+ in the reaction cycle of the human red cell membrane Ca2+-pump ATPase.
Lanthanum (La3+) inhibits the Ca-pump of the red cell by arresting the protein in a phosphorylated form (PI). Similar La3+ concentrations are required to increase the amount of PI and to stop PI-decay. In the presence of La3+ phosphorylation becomes insensitive to Mg2+. PI made in the presence of Mg2+ is not prevented from decaying by subsequent addition of La3+, whereas that made in the absence of Mg2+ is. Taken together, these findings seem to indicate that La3+ blocks the transition between a 1st and a 2nd form of PI.
D001693:Biological Transport, Active / Q000187:drug effects; D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D004305:Dose-Response Relationship, Drug; D004910:Erythrocyte Membrane / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D007473:Ion Channels / Q000201:enzymology*; D007811:Lanthanum / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology; D010766:Phosphorylation
D007473:Ion Channels; D007811:Lanthanum; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D008274:Magnesium; D002118:Calcium