Barfoot, M.; Fajardo, V.; Braun, J. L.

Phospholamban and sarcolipin are two key regulators of the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) that have been shown to protect SERCA from thermal inactivation in muscle. We have recently detected neuronatin (NNAT) in murine skeletal muscle and have shown that it too regulates SERCA. Here, we questioned whether NNAT would also protect SERCA from thermal inactivation. In response to 60 min of heat stress at 40C, maximal SERCA activity was significantly reduced in soleus homogenates obtained from NNAT knockout mice (-23%) but not wild-type mice (-5%). Our results add further support for NNATs role in regulating SERCA function in murine muscle.