Structural basis of the relaxed state of a Ca2+-regulated myosin filament and its evolutionary implications.

ABSTRACT: Myosin filaments of muscle are regulated either by phosphorylation of their regulatory light chains or Ca(2+) binding to the essential light chains, contributing to on-off switching or modulation of contraction. Phosphorylation-regulated filaments in the relaxed state are characterized by an asymmetric interaction between the two myosin heads, inhibiting their actin binding or ATPase activity. Here, we have tested whether a similar interaction switches off activity in myosin filaments regulated by Ca(2+) binding. Cryo-electron microscopy and single-particle image reconstruction of Ca(2+)-regulated (scallop) filaments reveals a helical array of myosin head-pair motifs above the filament surface. Docking of atomic models of scallop myosin head domains into the motifs reveals that the heads i

SUBMITTER: Woodhead JL 

PROVIDER: S-EPMC3666738 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature