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Monitoring ER/SR Calcium Release with the Targeted Ca2+ Sensor CatchER+
Published on: May 19, 2017
The dimeric form of Ca2+-ATPase is involved in Ca2+ transport in the sarcoplasmic reticulum
Makoto Ushimaru1, Yoshihiro Fukushima
1Department of Chemistry, Kyorin University School of Medicine, Shinkawa 6-20-2, Mitaka, Tokyo, Japan. ushimaru@kyorin-u.ac.jp
Abstract:
To identify the functional unit of Ca(2+)-ATPase in the sarcoplasmic reticulum, we assessed Ca(2+)-transport activities occurring on sarcoplasmic reticulum membranes with different combinations of active and inactive Ca(2+)-ATPase molecules. We prepared heterodimers, consisting of a native Ca(2+)-ATPase molecule and a Ca(2+)-ATPase molecule inactivated by FITC labelling, by fusing vesicles loaded with each type of Ca(2+)-ATPase. The heterodimers exhibited neither Ca(2+) transport nor ATP hydrolysis, suggesting that Ca(2+) transport by the Ca(2+)-ATPase requires an interaction between functional Ca(2+)-ATPase monomers. This finding implies that the functional unit of the Ca(2+)-ATPase is a dimer.
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