Ca-ATPase of human myometrium plasma membranes.
We determined and characterized the Mg2+-dependent, Ca2+-stimulated ATPase (Ca-ATPase) activity in cell plasma membranes from the myometrium of pregnant women, and compared these characteristics to those of the active Ca2+-transport already demonstrated in this tissue. Similarly to the Ca2+-transport system, the Ca2+-ATPase is Mg2+-dependent, stimulated by calmodulin, and inhibited by vanadate. The Km for Ca2+ activation is 0.40 microM, very similar to that found for active calcium transport, i.e. 0.25 microM. Consequently, this Ca2+-ATPase can be responsible for the active calcium transport across the plasma membranes of smooth muscle cells.
Carrera
F
F
Biophysical and Biochemical Center, Venezuelan Institute for Scientific Investigation, Maternity Hospital Concepción Palacios Caracas.
Proverbio
T
T
Marín
R
R
Proverbio
F
F
D015720:5'-Nucleotidase / Q000032:analysis / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D002118:Calcium / Q000493:pharmacokinetics; D000252:Calcium-Transporting ATPases / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D002147:Calmodulin / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D006868:Hydrolysis; D008274:Magnesium / Q000494:pharmacology; D009215:Myometrium / Q000201:enzymology*; D009251:NADPH-Ferrihemoprotein Reductase / Q000032:analysis / Q000378:metabolism; D011247:Pregnancy; D013347:Subcellular Fractions / Q000201:enzymology; D014638:Vanadates / Q000494:pharmacology
D002147:Calmodulin; D004791:Enzyme Inhibitors; D014638:Vanadates; D000255:Adenosine Triphosphate; D009251:NADPH-Ferrihemoprotein Reductase; D015720:5'-Nucleotidase; D000252:Calcium-Transporting ATPases; D008274:Magnesium; D002118:Calcium