For example, the Bcl-2 family protein BCL2L13, when elevated by endurance training, localizes to ER-mitochondria junctions and supports Ca2+ signaling: loss of BCL2L13 (in zebrafish or C2C12 myotubes) blunts mitochondrial Ca2+ uptake and impairs muscle performance.116 In this way, exercise-induced MERC remodeling (both structural and molecular) enhances Ca2+ handling and bioenergetic coupling, helping to mitigate sarcopenia-related muscle decline by preserving excitation–contraction efficiency and mitochondrial quality.98,116. This evidence concerns the gene BCL2L13 and sarcopenia.