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The N-terminal comprises a globular head in the heavy chains, and the C-terminal ends with an alpha helix.  The globular head region is also known as S1, and also contains mostly alpha-helices that are critical to maintaining structure.  The C-terminal end contains interspersed hydrophobic regions that give rise to a "coiled coil" structure.<ref name="CHEM43" />

The actin-binding, catalytic site of myosin is known as S1 (subfragment 1).  This is the amino-terminal globular head portion of the myosin molecule.  The S1 head is divided into three subdomains: the NH2-terminal 25 kDa region, a central 50 kDa region, and the COOH-terminal 20 kDa region.  Further analysis of the S1 active site of myosin suggests that the γ-phosphate (of ATP) binds near the apex of the 50 kDa cleft.  It is believed to be a region critical to function, because of the presence of evolutionarily conserved residues along the central cleft.<ref name="Ruppel" />  The actin-binding site and nucleotide-binding site, although dominated by alpha-helices, also contains a straightened section with two cysteine residues.  The can form a disulfide bond in the presence of a nucleotide that prevents ADP from leaving the active site.