Static μT-Level Magnetic Fields Modulate Myosin Phosphorylation via Kinetic Effects on Calcium Binding to Calmodulin

Abstract

Signal transduction as triggered by ligand gated binding of hormones, antigen molecules, growth factors and other cell-surface agonists is a key pathway for the activation, differentiation and proliferation of many cell types1. Calcium ion binding is emerging as essential in the transduction of exogenous electromagnetic field (EMF) signals into physiological responses through modulation of relevant biochemical cascades2,3. Calcium dependent steps in the target pathway may include: (i) initial detection of EMF with resultant electrochemical changes at specific binding sites; (ii) membrane bound proteins signaling to the cell interior; (iii) EMF coupling with the cytoskeleton and other subcellular constituents. Four groups of intracellular enzymes have been reported to respond to membrane signals from EMF: (i) membrane-bound adenylate cyclase involved in activation of protein kinase through conversion of ATP to cAMP in bone cells4,5; (ii) cAMP-independent protein kinase that performs messenger functions6; (iii) ornithine decarboxylase, necessary for cell growth and involved in synthesis of polyamines which are essential for DNA formation; (iv) myosin light chain kinase, involved in muscle contraction 8–11.