By a News Reporter-Staff News Editor at Life Science Weekly -- Current study results on Myosins have been published. According to news reporting originating from Calgary, Canada, by NewsRx correspondents, research stated, "During activation of smooth muscle contraction, one myosin light chain kinase (MLCK) molecule rapidly phosphorylates many smooth muscle myosin (SMM) molecules, suggesting that muscle activation rates are influenced by the kinetics of MLCK-SMM interactions. To determine the rate-limiting step underlying activation of SMM by MLCK, we measured the kinetics of calcium-calmodulin (Ca2+CaM)-MLCK-mediated SMM phosphorylation and the corresponding initiation of SMM-based F-actin motility in an in vitro system with SMM attached to a coverslip surface."
Our news editors obtained a quote from the research from the University of Calgary, "Fitting the time course of SMM phosphorylation to a kinetic model gave an initial phosphorylation rate, k(p)(o), of similar to 1.17 heads s(-1) MLCK-1. Also, we measured the dwell time of single streptavidin-coated quantum dot-labeled MLCK molecules interacting with surface-attached SMM and phosphorylated SMM using total internal reflection fluorescence microscopy. From these data, the dissociation rate constant from phosphorylated SMM was 0.80 s(-1), which was similar to the k(p)(o) mentioned above and with rates measured in solution. This dissociation rate was essentially independent of the phosphorylation state of SMM. From calculations using our measured dissociation rates and K-d values, and estimates of SMM and MLCK concentrations in muscle, we predict that the dissociation of MLCK from phosphorylated SMM is rate-limiting and that the rate of the phosphorylation step is faster than this dissociation rate. Also, association with SMM (11-46 s(-1)) would be much faster than with pSMM (
According to the news editors, the research concluded: "This would avoid sequestering MLCK to unproductive interactions with previously phosphorylated SMM, potentially leading to faster rates of phosphorylation in muscle."
For more information on this research see: Kinetics of Myosin Light Chain Kinase Activation of Smooth Muscle Myosin in an in Vitro Model System. Biochemistry, 2013;52(47):8489-8500. Biochemistry can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Biochemistry - www.pubs.acs.org/journal/bichaw)
The news editors report that additional information may be obtained by contacting F. Hong, University of Calgary, Fac Med, Dept. of Biochem & Mol Biol, Calgary, AB T2N 4N1, Canada. Additional authors for this research include K.C. Facemyer, M.S. Carter, D.R. Jackson, B.D. Haldeman, N. Ruana, C. Sutherland, M.P. Walsh, C.R. Crerno and J.E. Baker (see also Myosins).
Keywords for this news article include: Canada, Calgary, Alberta, Biopolymers, Myosin Type II, Muscle Proteins, Myosin Light Chains, Phosphotransferases, Contractile Proteins, Cytoskeletal Proteins, Enzymes and Coenzymes, Smooth Muscle Myosins, Microfilament Proteins, Calcium-Binding Proteins, Molecular Motor Proteins, North and Central America
Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC