A globular subunit of microfilaments, highly conserved Actin is one of the most abundant proteins in eukaryotic cells. Monomeric actin, a slow ATPase composed of a 375 amino acid polypeptide chain, interacts with one molecule of ATP or ADP and contains high affinity and low affinity binding sites for divalent cations. Actin can quickly assemble into long microfilament polymers. In conjunction with myosin, actin is responsible for the contraction and relaxation of muscle.

Globular subunit of microfilaments, whose ATP-dependent polymerization and movement underlies many dynamic cellular phenomena in addition to muscle contraction; actin is one of the most abundant proteins in eukaryotic cells.

One of the proteins that allows cells to move and muscles to contract.

Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.

Actin, protein that is an important contributor to the contractile property of muscle and other cells. It exists in two forms: G-actin (monomeric globular actin) and F-actin (polymeric fibrous actin), the form involved in muscle contraction. In muscle, two long strands of beadlike actin molecules...