Tropomyosin from adult human skeletal muscle is partially phosphorylated

Alpha and beta tropomyosins were isolated from postmortem adult human psoas and pectoralis major muscles. 31P nuclear magnetic resonance and amino acid analysis were used to show that 10% of the major alpha tropomyosin component was phosphorylated. The 31P NMR spectra also suggested that human beta tropomyosin was phosphorylated, but to a lesser extent.