Ca2+-ATPase of sarcoplasmic reticulum is known to pump Mn2+ in addition to Ca2+, but whether its transport mechanism is identical to that of Ca2+ is ambiguous. To clarify, we examined, by atomic absorption spectroscopy, competition between Mn2+ and Ca2+ in active transport using vesicles of sarcoplasmic reticulum (SR). Here, we demonstrate that Ca2+-ATPase transports Ca2+ and Mn2+ concomitantly but has a much lower affinity for Mn2+ (apparent Kd ~ 0.5 mm). Stoichiometries of transported ions per ATP hydrolysed, Vmax values and activation energies are very similar. Altogether, Ca2+-ATPase appears to use the same mechanism for transporting Mn2+ as that for Ca2+.
CITATION STYLE
Yonekura, S. I., & Toyoshima, C. (2016). Mn2+ transport by Ca2+-ATPase of sarcoplasmic reticulum. FEBS Letters, 2086–2095. https://doi.org/10.1002/1873-3468.12244
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