Some properties of the Ca2+-stimulated ATPase of a rat liver microsomal fraction.

نویسندگان

  • A P Dawson
  • D V Fulton
چکیده

1. The heavy microsomal fraction from rat liver apparently has very little Ca2+-stimulated ATPase activity, although it has an active, ATP-driven Ca2+ accumulation system. 2. The addition of ionophore A23187 to the ATPase assay, to allow continuous Ca2+ recycling during the assay time, reveals the presence of a substantial Ca2+-stimulated ATPase with Vmax. 160 nmol of Pi/10 min per mg of protein and Km for Ca2+ 0.19 microM. 3. The Ca2+-stimulated ATPase, but not the basal Mg2+-stimulated ATPase, is potently inhibited by orthovanadate. Both the Ca2+-stimulated ATPase and the vanadate inhibition are enhanced by the presence of Mg2+. 4. Ca2+-stimulated ATPase activity is not responsive to calmodulin or the calmodulin antagonist trifluoperazine.

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عنوان ژورنال:
  • The Biochemical journal

دوره 210 2  شماره 

صفحات  -

تاریخ انتشار 1983