The average heart beats 35 million times a year – 2.5 billion times over a lifetime. Those beats must be precisely calibrated; even a small divergence from the metronomic rhythm can cause sudden death. For decades, scientists have wondered exactly how the heart stays so precisely on rhythm even though it contains so many moving parts. Now, researchers at the University of Maryland School of Medicine (UM SOM) have helped identify how a particular protein plays a central role in this astonishing consistency. This is the first time the mechanism has been described; the discovery could eventually help scientists treat heart problems that kill millions of people every year.