Trypsin activation of the red cell Ca2+-pump ATPase is calcium-sensitive
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Updated: Oct 23, 2026

Monitoring ER/SR Calcium Release with the Targeted Ca2+ Sensor CatchER+
Published on: May 19, 2017
Abstract:
Stimulation of the calmodulin-independent activity of the red cell Ca2+-pump ATPase by trypsin treatment (of calmodulin free red cell membranes) is sensitive to Ca2+ in a concentration range near the KCa of the transport site. The Ca2+ requirement for this effect is absolute, whereas the calmodulin sensitivity of the ATPase can be abolished by sufficient trypsin attack in the absence of Ca2+, although Ca2+ accelerates inactivation. This indicates that the two effects of trypsin are due to at least two distinct cleavage sites in the pump protein.
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