ANATOMY

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: -Actin. The thin filament consists of two intertwined bands of actin monomers. Both skeletal and cardiac forms of actin are present during human cardiac development.

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).

Detailed explanation-4: -Myofilaments make up the myofibril. The myofibrils are contractile threads that extend along the length inside the striated muscle fiber.