The inhibitors thapsigargin and 2,5-di(tert-butyl)-1,4-benzohydroquinone favour the E2 form of the Ca2+,Mg(2+)-ATPase

FEBS Lett. 1992 Jun 15;304(2-3):109-13. doi: 10.1016/0014-5793(92)80599-c.

Abstract

2,5-Di(tert-butyl)-1,4-benzohydroquinone has been shown to inhibit the Ca2+,M(2+)-ATPase of sarcoplasmic reticulum with an affinity of 0.4 microM. It has been shown to shift the E2-E1 equilibrium for the ATPase towards E2, as shown previously for the inhibitor thapsigargin. The shift towards E2 results in a decrease in affinity for Ca2+, as also observed for thapsigargin. A marked decrease in the rate of the E2-E1 transition is observed for both BHQ and thapsigargin. A decrease in the equilibrium level of phosphorylation by Pi and of the steady-state level of phosphorylation by ATP are consistent with a decrease in the equilibrium constant for phosphorylation by Pi and an increase in the rate of dephosphorylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ca(2+) Mg(2+)-ATPase / antagonists & inhibitors
  • Ca(2+) Mg(2+)-ATPase / metabolism*
  • Calcium / metabolism
  • Calcium-Transporting ATPases / antagonists & inhibitors
  • Calcium-Transporting ATPases / metabolism*
  • Hydroquinones / pharmacology*
  • Kinetics
  • Sarcoplasmic Reticulum / enzymology*
  • Spectrometry, Fluorescence
  • Terpenes / pharmacology*
  • Thapsigargin
  • Vanadates / pharmacology

Substances

  • Hydroquinones
  • Terpenes
  • 2,5-di-tert-butylhydroquinone
  • Vanadates
  • Thapsigargin
  • Ca(2+) Mg(2+)-ATPase
  • Calcium-Transporting ATPases
  • Calcium