Interacting-heads motif has been conserved since before the origin of animals

What is it about?

All animals have the ability to move. Myosin II is the motor protein that generates this movement by powering muscular contraction; it also drives motility in nonmuscle cells. In relaxed muscle and in quiescent nonmuscle cells, myosin II is switched off by intramolecular interactions between its heads that inhibit its activity. This interacting-heads motif (IHM) is a fundamental contributor to contractile regulation. Given its importance in cell contractility, we wanted to determine when the IHM first evolved. Using electron microscopy, image averaging, and sequence analysis of myosin II from primitive organisms, we show that the IHM has existed since the earliest animals and before. This ancient origin highlights the central role of the IHM in regulating myosin II function.

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Why is it important?

This ancient origin highlights the central role of the IHM in regulating myosin II function.