are actin and myosin proteins
1 During contraction, the myosin molecule forms a chemical bond with an actin molecule on the thin filament (gripping the rope). 2  This chemical bond is the crossbridge. 3  For clarity, only one cross-bridge is shown in the figure above (focusing on one arm). During contraction, the thin filaments slide past the thick filaments, shortening the sarcomere. The thick and thin filaments do the actual work of a muscle, and the way they do this is pretty cool. Thick filaments are made of a protein called myosin. At the molecular level, a thick filament is a shaft of myosin molecules arranged in a cylinder. Thin filaments are made of another protein called actin. The thin filaments look like two strands of pearls twisted around each other. Actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape. Each myosin thick filament is surrounded by actin thin filaments, and each thin filament is surrounded by thick filaments. Several of these filament bundles make up the functional portion of a muscle cell. It is also important to note that the thin filaments are attached to a very dense protein plate called a Z disc. The eukaryotes seem to contain a major amount of motor proteins. These motor proteins are found to be in great coordination with the actin filaments. They are known as the Myosin. Myosin can be subdivided as Myosin 1 and Myosin 2. Myosin 1 possesses the contractile property like the actins and hence helps in muscle contraction. Troponin is a protein that helps hold tropomyosin in place on the actin filament. A muscle contraction consists of a series of repeated events. First, calcium triggers a change in the shape of troponin and reveals the myosin-binding sites of actin beneath tropomyosin. The main contractile system of all muscular tissue are based on the interactions of two proteins Actin and Myosin. The system of these proteins some times called actin-myosin contractile system. Actin is one of the most condensed forms of protein, which is globular and is a monomeric subunit of microfilament. The thin filaments in actin constitute a major part of it. Actin is a spherical protein that forms filaments, which are involved in muscle contraction and other important cellular processes. Tropomyosin is a long strand that loops around the actin chains in the thin filament. Troponin is a protein that helps hold tropomyosin in place on the actin filament. For a muscle contraction to occur, troponin and tropomyosin must be moved to reveal the myosin-binding sites. Calcium triggers movement of these proteins. Actin rules over cell functions which include cell division, morphing of the shape of the cells, cell mobility and other contractile properties. It is a 42 kDa protein and related gene has 100 nucleotides. The attraction between the myosin head and the myosin-binding site of actin are strong enough that the bond can form spontaneously. Once the two proteins are bound, the myosin protein undergoes a conformational change, or a change in protein shape, that 'cocks' the head.
Yes