GENERAL HISTOLOGY

Detailed explanation-1: -Thin myofilaments are 1 m long and 8 nm in diameter, consisting primarily of actin. Actin is a globular protein with a molecular weight of 43 kDa. Two F-actin strands twisted in a double helix form the backbone of the thin myofilament and possess a complementary binding site for the myosin globular head.

Detailed explanation-2: -Myofilaments (see also Chapter 3) The myofilament contractile proteins consist of thick filament myosin and thin filament actin proteins. Bound to actin are a complex of regulatory proteins, which include tropomyosin and troponin-T, C, and I.

Detailed explanation-3: -Actin filaments (F-actin) are linear polymers of globular actin (G-actin) subunits and occur as microfilaments in the cytoskeleton and as thin filaments, which are part of the contractile apparatus, in muscle and nonmuscle cells (see contractile bundles).