Michael Barfoot

1 INTRODUCTION Skeletal muscle constitutes 40%–50% of total body mass and is vital for daily functions such as mobility and metabolism (Frontera & Ochala, 2015; Wolfe, 2006). The significance of skeletal muscle is evident in conditions such as sarcopenia—age-related losses in muscle mass and strength—that repeatedly serve as a significant independent predictor of all-cause mortality (Benz et al., 2024; Brown et al., 2016; Zhang et al., 2018; Zhou et al., 2023).

Abstract 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.