Lee KH, Sulbar?n G, Yang S, Mun JY, Alamo L, Pinto A, Sato O, Ikebe M, Liu X, Korn ED, Sarsoza F, Bernstein SI, Padr?n R, Craig R. Interacting-heads motif has been conserved as a mechanism of myosin II inhibition since before the origin of animals. Proc Natl Acad Sci U S A. 2018 02 27; 115(9):E1991-E2000.