Biomaterial Database

Regulation of the actin-activated ATPase activity of Acanthamoeba myosin I by cross-linking actin filaments. 1986

J P Albanesi, and T J Lynch, and H Fujisaki, and E D Korn

The actin-activated Mg2+-ATPase activity of phosphorylated Acanthamoeba myosin I was previously shown to be cooperatively dependent on the myosin concentration (Albanesi, J. P., Fujisaki, H., and Korn, E. D. (1985) J. Biol. Chem. 260, 11174-11179). This observation was rationalized by assuming that myosin I contains a high-affinity and a low-affinity F-actin-binding site and that binding at the low-affinity site is responsible for the actin-activated ATPase activity. Therefore, enzymatic activity would correlate with the cross-linking of actin filaments by myosin I, and the cooperative increase in specific activity at high myosin:actin ratios would result from the fact that cross-linking by one myosin molecule would increase the effective F-actin concentration for neighboring myosin molecules. This model predicts that high specific activity should occur at myosin:actin ratios below that required for cooperative interactions if the actin filaments are cross-linked by catalytically inert cross-linking proteins. This prediction has been confirmed by cross-linking actin filaments with either of three gelation factors isolated from Acanthamoeba, one of which has not been previously described, or by enzymatically inactive unphosphorylated Acanthamoeba myosin I.

UI	MeSH Term	Description	Entries
D008840	Microfilament Proteins	Monomeric subunits of primarily globular ACTIN and found in the cytoplasmic matrix of almost all cells. They are often associated with microtubules and may play a role in cytoskeletal function and/or mediate movement of the cell or the organelles within the cell.	Actin Binding Protein,Actin-Binding Protein,Actin-Binding Proteins,Microfilament Protein,Actin Binding Proteins,Binding Protein, Actin,Protein, Actin Binding,Protein, Actin-Binding,Protein, Microfilament,Proteins, Actin-Binding,Proteins, Microfilament
D009218	Myosins	A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.	Myosin ATPase,ATPase, Actin-Activated,ATPase, Actomyosin,ATPase, Myosin,Actin-Activated ATPase,Actomyosin ATPase,Actomyosin Adenosinetriphosphatase,Adenosine Triphosphatase, Myosin,Adenosinetriphosphatase, Actomyosin,Adenosinetriphosphatase, Myosin,Myosin,Myosin Adenosinetriphosphatase,ATPase, Actin Activated,Actin Activated ATPase,Myosin Adenosine Triphosphatase
D010766	Phosphorylation	The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.	Phosphorylations
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D003432	Cross-Linking Reagents	Reagents with two reactive groups, usually at opposite ends of the molecule, that are capable of reacting with and thereby forming bridges between side chains of amino acids in proteins; the locations of naturally reactive areas within proteins can thereby be identified; may also be used for other macromolecules, like glycoproteins, nucleic acids, or other.	Bifunctional Reagent,Bifunctional Reagents,Cross Linking Reagent,Crosslinking Reagent,Cross Linking Reagents,Crosslinking Reagents,Linking Reagent, Cross,Linking Reagents, Cross,Reagent, Bifunctional,Reagent, Cross Linking,Reagent, Crosslinking,Reagents, Bifunctional,Reagents, Cross Linking,Reagents, Cross-Linking,Reagents, Crosslinking
D000199	Actins	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.	F-Actin,G-Actin,Actin,Isoactin,N-Actin,alpha-Actin,alpha-Isoactin,beta-Actin,gamma-Actin,F Actin,G Actin,N Actin,alpha Actin,alpha Isoactin,beta Actin,gamma Actin
D000205	Actomyosin	A protein complex of actin and MYOSINS occurring in muscle. It is the essential contractile substance of muscle.
D000656	Amoeba	A genus of ameboid protozoa. Characteristics include a vesicular nucleus and the formation of several PSEUDOPODIA, one of which is dominant at a given time. Reproduction occurs asexually by binary fission.	Ameba
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D017301	Ca(2+) Mg(2+)-ATPase	An enzyme that catalyzes the hydrolysis of ATP and is activated by millimolar concentrations of either Ca(2+) or Mg(2+). Unlike CA(2+)-TRANSPORTING ATPASE it does not require the second divalent cation for its activity, and is not sensitive to orthovanadate. (Prog Biophys Mol Biol 1988;52(1):1). A subgroup of EC 3.6.1.3.	ATPase, Calcium Magnesium,ATPase, Magnesium,Adenosinetriphosphatase, Calcium, Magnesium,Adenosinetriphosphatase, Magnesium,Calcium Magnesium ATPase,Calcium Magnesium Adenosinetriphosphatase,Magnesium ATPase,Magnesium Adenosinetriphosphatase,Adenosine Triphosphatase, Calcium, Magnesium,Adenosine Triphosphatase, Magnesium,Ca Mg-ATPase,Ca2+-Mg2+ ATPase,Calcium Magnesium Adenosine Triphosphatase,Mg2+-ATPase,Mg2+-Dependent ATPase,ATPase, Ca2+-Mg2+,ATPase, Mg2+-Dependent,Adenosinetriphosphatase, Calcium Magnesium,Ca Mg ATPase,Ca2+ Mg2+ ATPase,Magnesium Adenosine Triphosphatase,Mg2+ ATPase,Mg2+ Dependent ATPase