Biomaterial Database

The mechanism for the inhibition of actin-activated ATPase of smooth muscle heavy meromyosin by calponin. 1991

K Y Horiuchi, and S Chacko

Department of Pathobiology, University of Pennsylvania, Philadelphia 19104.

Calponin, an actin-binding protein, inhibited the acto-heavy meromyosin (HMM) MgATPase and lowered the binding of HMM to actin. The amount of calponin bound to actin or tropomyosin-actin was the same when the ATPase was inhibited 80-90%. While the KATPase was diminished only less than 2-fold in the presence of calponin, the Vmax was decreased 6-fold and 2-fold with actin and tropomyosin-actin, respectively. A comparison of the kinetic constants for the ATP hydrolysis obtained in the presence of actin-calponin and tropomyosin-actin-calponin revealed that the tropomyosin augmented the Vmax 5-fold from the inhibited level, but there was no effect on the KATPase.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
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
D009124	Muscle Proteins	The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.	Muscle Protein,Protein, Muscle,Proteins, Muscle
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D002135	Calcium-Binding Proteins	Proteins to which calcium ions are bound. They can act as transport proteins, regulator proteins, or activator proteins. They typically contain EF HAND MOTIFS.	Calcium Binding Protein,Calcium-Binding Protein,Calcium Binding Proteins,Binding Protein, Calcium,Binding Proteins, Calcium,Protein, Calcium Binding,Protein, Calcium-Binding
D002645	Chickens	Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.	Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D005895	Gizzard, Avian	The posterior portion of the avian stomach located between the PROVENTRICULUS and INTESTINE. It consists of a thick muscular wall and small stones (gastroliths) that function to mechanically grind SEEDS and other ingested objects.	Gizzard,Ventriculus,Avian Gizzard,Avian Gizzards,Gizzards,Gizzards, Avian
D000096985	Calponins	A family of actin binding proteins mostly in smooth muscle. Calponins include most abundant alpha-calponin (h1 or basic); beta-calponin; neutral calponin (h2 calponin); acidic calponin, SM22, and transgelin. Calponin family members have N-terminal single Calponin Homology (CH) domain and multiple C-terminus 23-amino acids long calponin-like repeats called CLICK-23. Calponins participate in modulation of smooth muscle contraction by binding to ACTINS (F- and G-Actins), CALMODULIN and TROPOMYSIN.	Calponin,Calponin Family Proteins