Regulatory light chains modulate in vitro actin motility driven by skeletal heavy meromyosin

► Contractile modulation via skeletal myosin regulatory light chains (RLCs) in vitro. ► Phosphorylation of myosin RLCs may control actin motility in nanotech-applications. ► Calcium modulates myosin induced actin sliding in absence troponin and tropomyosin. ► Independent mechanisms of Ca-binding and phosphorylation of skeletal myosin RLCs.