Structure and orientation of troponin in the thin filament.

ABSTRACT: The troponin complex on the thin filament plays a crucial role in the regulation of muscle contraction. However, the precise location of troponin relative to actin and tropomyosin remains uncertain. We have developed a method of reconstructing thin filaments using single particle analysis that does not impose the helical symmetry of actin and is independent of a starting model. We present a single particle three-dimensional reconstruction of the thin filament. Atomic models of the F-actin filament were fitted into the electron density maps and troponin and tropomyosin located. The structure provides evidence that the globular head region of troponin labels the two strands of actin with a 27.5-A axial stagger. The density attributed to troponin appears tapered with the widest point toward t

SUBMITTER: Paul DM 

PROVIDER: S-EPMC2685683 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature