title: [Characterization of the calcium transport cycle of sarcoplasmic reticulum by inorganic phosphate including the function of magnesium (author's transl)].
abstract: The present study presents experiments on ATP-Pi exchange and phosphorylation of the calcium-transport-ATPase of sarcoplasmic reticulum vesicles by orthophosphate under conditions of ATP-Pi exchange, as well as on Ca-independent and Ca-dependent phosphorylation in the absence of ATP, ADP and calcium outside. The rate of the ATP-Pi exchange correlates with the phosphoprotein steady state level labelled from orthophosphate. Ca-independent phosphorylation is due to magnesium-phosphoprotein formation and Ca-dependent phosphorylation is due to magnesium-calcium-phosphoprotein formation. A reaction sequence which probably accounts for phosphorylation of the transport enzyme by orthophosphate and its significance in characterizing the intermediate steps of the calcium transport cycle is discussed.
mesh_terms: D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D066298:In Vitro Techniques; D008274:Magnesium / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism; D051381:Rats; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
chemical_list: D010710:Phosphates; D008274:Magnesium; D002118:Calcium
vernacular_title: Uber die durch Orthophosphat charakterisierbare Reaktionssequenz des Calciumtransportzyklus sarkoplasmatischer Retikulummembranen unter Einbeziehung der Funktion des Magnesiums.