title: The influence of caldesmon on ATPase activity of the skeletal muscle actomyosin and bundling of actin filaments.
abstract: Chicken gizzard caldesmon causes up to 40% inhibition of Mg2+-ATPase activity of rabbit skeletal muscle actomyosin. In the presence of chicken gizzard tropomyosin this inhibition is significantly increased, reaching a maximum (around 80%) at a molar ratio of caldesmon to actin monomer of 1 to 10-13. The inhibition of actomyosin ATPase takes place over a wide pH range (from 6.0 to 8.0) but is decreased with an increase in KCl and MgCl2 concentrations. Caldesmon, in the range of caldesmon/ actin ratios within which it inhibits actomyosin ATPase, forms bundles of parallelly aligned actin filaments. Calmodulin in the presence of Ca2+ dissociates these bundles and restrains the inhibition of actomyosin ATPase, provided that it is used at a high molar excess over caldesmon.
authors.forename: R
authors.initials: R
authors.lastname: Dabrowska
authors.forename: A
authors.initials: A
authors.lastname: Goch
authors.forename: B
authors.initials: B
authors.lastname: Gałazkiewicz
authors.forename: H
authors.initials: H
authors.lastname: Osińska
mesh_terms: D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000205:Actomyosin / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002645:Chickens; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008840:Microfilament Proteins / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D011817:Rabbits; D014335:Tropomyosin / Q000378:metabolism
chemical_list: D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D008840:Microfilament Proteins; D014335:Tropomyosin; D011189:Potassium Chloride; D000205:Actomyosin; D000251:Adenosine Triphosphatases; D008274:Magnesium