title: Purification of a novel Ca-binding protein that inhibits myosin light chain kinase activity in lower eukaryote Physarum polycephalum.
abstract: Myosin light chain kinase (MLCK) was partially purified from the lower eukaryote Physarum polycephalum. The activity to phosphorylate Physarum myosin was maximal in the absence of Ca2+ and decreased with an increase in Ca2+ concentration with a microM-level Kd. The Ca-binding protein contained in the MLCK preparation was purified to homogeneity. The native protein had a molecular mass of 75 kDa, while under denaturing conditions, it was 38 kDa. Ca-dependent changes in the intensities of intrinsic fluorescence showed that the Kd of the protein for Ca2+ was also in the microM-range. Our results suggest that the Ca-binding protein would play a key role in the effects of Ca2+ in the MLCK preparation.
authors.affiliation: Department of Pharmacology, Gunma University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Okagaki
authors.forename: R
authors.initials: R
authors.lastname: Ishikawa
authors.forename: K
authors.initials: K
authors.lastname: Kohama
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000737:chemistry* / Q000302:isolation & purification; D005470:Fluorometry; D008970:Molecular Weight; D009219:Myosin-Light-Chain Kinase / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D010804:Physarum / Q000187:drug effects / Q000201:enzymology
chemical_list: D002147:Calmodulin; D009219:Myosin-Light-Chain Kinase; D002118:Calcium