AIF4-induced inhibition of the ATPase activity, the Ca2+-transport activity and the phosphoprotein-intermediate formation of plasma-membrane and endo(sarco)plasmic-reticulum Ca2+-transport ATPases in different tissues. Evidence for a tissue-dependent functional difference.
AIF4- inhibits the (Ca2+ + Mg2+)-ATPase activity of the plasma-membrane and the sarcoplasmic-reticulum Ca2+-transport ATPase [Missiaen, Wuytack, De Smedt, Vrolix & Casteels (1988) Biochem. J. 253, 827-833]. The aim of the present work was to investigate this inhibition further. We now report that AIF4- inhibits not only the (Ca2+ + Mg2+)-ATPase activity, but also the ATP-dependent 45Ca2+ transport, and the formation of the phosphoprotein intermediate by these pumps. Mg2+ potentiated the effect of AIF4-, whereas K+ had no such effect. The plasma-membrane Ca2+-transport ATPase from erythrocytes was 20 times less sensitive to inhibition by AIF4- as compared with the Ca2+-transport ATPase from smooth muscle. The endoplasmic-reticulum Ca2+-transport ATPase from smooth muscle was inhibited to a greater extent than the sarcoplasmic-reticulum Ca2+-transport ATPase of slow and fast skeletal muscle.
Missiaen
L
L
Department of Physiology, Catholic University of Leuven, Belgium.
Wuytack
F
F
De Smedt
H
H
Amant
F
F
Casteels
R
R
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000535:Aluminum / Q000494:pharmacology*; D017607:Aluminum Compounds; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000493:pharmacokinetics*; D002462:Cell Membrane / Q000201:enzymology*; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D004910:Erythrocyte Membrane / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology; D005459:Fluorides / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000201:enzymology / Q000648:ultrastructure; D010750:Phosphoproteins / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D013552:Swine
D017607:Aluminum Compounds; D010750:Phosphoproteins; D000535:Aluminum; D000251:Adenosine Triphosphatases; D005459:Fluorides; D002118:Calcium; C032311:aluminum fluoride