Changing face of contractile activation in striated muscle at physiological temperature.

Calcium binding to troponin, with subsequent displacement of its linked tropomyosin molecule on the thin filament surface, cooperates with myosin binding to actin in the contractile regulation of striated muscle. The intertwined role of these systems is studied in the present issue of JGP by Ishii et al. (https://doi.org/10.1085/jgp.202313414). A particularly interesting feature of the paper, except for studying both skeletal and cardiac muscle proteins, is that the experiments unlike most other similar studies are performed at physiological temperature (35-40°C).