MICROANATOMY

Detailed explanation-1: -The major protein components of smooth muscle thin filaments are actin, tropomyosin and caldesmon, present in molar ratios of 28:4:1 respectively. Other smooth muscle proteins which may be associated with the thin filaments in the cell are filamin, vinculin, alpha-actinin, myosin light chain kinase and calmodulin.

Detailed explanation-2: -Thin Filaments The main component is the actin filament, which is formed from the polymerization of globular actin molecules. Each globular actin monomer contains a binding site for the globular myosin head. Along the entire length of the thin filament, actin monomers spiral around a structural protein called nebulin.

Detailed explanation-3: -A sarcomere is composed of two main protein filaments (thin actin and thick myosin filaments) which are the active structures responsible for muscular contraction.

Detailed explanation-4: -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).

Detailed explanation-5: -Two of the important proteins are myosin, which forms the thick filament, and actin, which forms the thin filament. Myosin has a long, fibrous tail and a globular head, which binds to actin. The myosin head also binds to ATP, which is the source of energy for muscle movement.