Figure 2

The 7-stranded β-sheet (green) and the adjacent structures (red). SNP substitution sites in the vicinity are depicted in grey or yellow with space filling models of the unsubstituted side chains. The yellow residues are also implicated in disease. SNP residue annotation color coding corresponds to: cardiac myosin II (red), skeletal myosin II (blue), non-muscle myosin II (brown), and unconventional myosin (tan). Residues annotated in black are not SNPs. The 7 strands are numbered at the tip indicating the sequence number increasing direction. R675 on β₃ (AA671-678); R170, E171, and N172 on β₄ (AA170-180); L463 on β₅ (AA458-468); and R252, I253, and T257 on β₆ (AA248-257) modify the structure. E681 is three residues past the end of β₃, E469 is on Switch 2 just two residues past the end of β₅, R240 and R246 are on Switch 1 just before the start of β₆, and T258 lies between β₆ and β₇ (AA265-271). Residues I88, E89, H98, E108, R445, and N447 are distant in sequence but spatially associated with the 7-stranded β-sheet structure. E89 is the most distant at ~7.5 angstroms. Blue side chains for residues Y458 and I460 are not SNPs but are proposed to contribute substantially to the energy barrier determining the rate limiting step to myosin ATPase product release in the absence of actin.