title: Isolation of the native form of chicken gizzard myosin light-chain kinase.
abstract: A simple and rapid procedure for the purification of the native form of chicken gizzard myosin light-chain kinase (Mr 136000) is described which eliminates problems of proteolysis previously encountered. During this procedure, a calmodulin-binding protein of Mr 141000, which previously co-purified with the myosin light-chain kinase, is removed and shown to be a distinct protein on the basis of lack of kinase activity, different chymotryptic peptide maps, lack of cross-reactivity with a monoclonal antibody to turkey gizzard myosin light-chain kinase, and lack of phosphorylation by the purified catalytic subunit of cyclic AMP-dependent protein kinase. This Mr-141000 calmodulin-binding protein is identified as caldesmon on the basis of Ca2+-dependent interaction with calmodulin, subunit Mr, Ca2+-independent interaction with skeletal-muscle F-actin, Ca2+-dependent competition between calmodulin and F-actin for caldesmon, and tissue content.
mesh_terms: D000818:Animals; D002118:Calcium; D002148:Calmodulin-Binding Proteins; D002645:Chickens; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005895:Gizzard, Avian / Q000201:enzymology; D008722:Methods; D009130:Muscle, Smooth / Q000201:enzymology*; D009219:Myosin-Light-Chain Kinase; D010446:Peptide Fragments / Q000032:analysis; D010749:Phosphoprotein Phosphatases / Q000302:isolation & purification; D011494:Protein Kinases / Q000302:isolation & purification*; D013379:Substrate Specificity
chemical_list: D002148:Calmodulin-Binding Proteins; D010446:Peptide Fragments; D011494:Protein Kinases; D009219:Myosin-Light-Chain Kinase; D010749:Phosphoprotein Phosphatases; D002118:Calcium