Myosin II filaments

Myosin II filaments are formed from bi-symmetrical bouquets of Myosin II dimers. Each dimer is tied together by a coiled-coil tail region which can mostly be removed by Chymotrypsin cleavage but the heads remain together. Further protease digestion with Papain removes the remainder of the tail (called the S2 region) leaving monomeric S1 heads which have the motor activity and both essential and regulatory light chain binding sites.