Collagen, type XVII, alpha 1 Collagen, type XVII, alpha 1 Collagen XVII, previously called BP180, is a transmembrane protein which plays a critical role in maintaining the linkage between the intracellular and the extracellular structural elements involved in epidermal adhesion. Collagen XVII is a homotrimer of three alpha1(XVII)-chains and a transmembrane protein in type II orientation. Each 180 kD a-chain contains a globular intracellular domain of approximately 70 kDa, which interacts with beta4-integrin, plectin, and BP230 and is necessary for the stable attachment of hemidesmosomes to keratin intermediate filaments. The large C-terminal ectodomain with a molecular mass of approximately 120 kDa consists of 15 collagenous
Myosin head Myosin head Muscle contraction is caused by the sliding action of thick filaments over thin filaments of the myofibril. Myosin is a major component of thick filaments and most myosin molecules are composed of a head, neck, and tail domain; the myosin head binds to thin filamentous actin, and uses ATP hydrolysis to generate force and "walk" along the thin filament. Myosin exists as a hexamer of two heavy chains, two alkali light chains, and two regulatory light chains. The heavy chain can be subdivided into the globular head at the N-terminal and the coiled-coil rod-like tail at the C-terminal,