title: Association of vanadate-sensitive Mg(2+)-ATPase and shape change in intact red blood cells.
abstract: Intact human erythrocytes, initially depleted of Mg2+ by EDTA incubation in the presence of A23187, exhibit Mg(2+)-dependent phosphate production of around 1.5 mmol per liter cells.h, half-maximally activated at around 0.4 mM added free Mg2+. This appears to correspond to Mg(2+)-stimulated adenosine triphosphatase (Mg(2+)-ATPase) activity found in isolated membranes, which is known to have a similar activity and affinity for Mg2+. Vanadate (up to 100 microM) inhibited Mg(2+)-dependent phosphate production and ATP breakdown in intact cells. Over a similar concentration range vanadate (3-100 microM) transformed intact cells from normal discocytes to echinocytes within 4-8 h at 37 degrees C, and more rapidly in Mg(2+)-depleted cells. The rate of Ca(2+)-induced echinocytosis was also enhanced in Mg(2+)-depleted cells. These results support previous studies in erythrocyte ghosts suggesting that vanadate-induced shape change is associated with inhibition of Mg(2+)-ATPase activity localized in the plasma membrane of the red blood cell.
authors.affiliation: Department of Biochemistry, University of Sydney, New South Wales, Australia.
authors.forename: Y H
authors.initials: YH
authors.lastname: Xu
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Lu
authors.forename: A D
authors.initials: AD
authors.lastname: Conigrave
authors.forename: M E
authors.initials: ME
authors.lastname: Auland
authors.forename: B D
authors.initials: BD
authors.lastname: Roufogalis
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D017301:Ca(2+) Mg(2+)-ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D004912:Erythrocytes / Q000166:cytology / Q000502:physiology*; D004913:Erythrocytes, Abnormal / Q000166:cytology / Q000502:physiology*; D006801:Humans; D008274:Magnesium / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D013997:Time Factors; D014638:Vanadates / Q000494:pharmacology*
chemical_list: D010710:Phosphates; D000001:Calcimycin; D014638:Vanadates; D000255:Adenosine Triphosphate; D017301:Ca(2+) Mg(2+)-ATPase; D008274:Magnesium; D002118:Calcium