Comparative analysis of phosphoprotein-enriched myocyte proteomes reveals widespread alterations during...

The differentiation of skeletal muscle has been associated with altered phosphorylation status of individual proteins. However, a global analysis of protein phosphorylation during myogenesis has yet to be undertaken. Here, we report the identification of over 130 putative phosphoproteins from murine C2C12 muscle cells. Cell extracts were fractionated on phosphoprotein enrichment columns and the resulting proteins were detected by two-dimensional gel electrophoresis and silver stain, and identified by liquid chromatography coupled to electrospray tandem mass spectrometry. The early differentiation of C2C12 myoblasts was found to be accompanied by changes in the phosphorylation or expression of numerous proteins including cytoskeletal, heat shock and signaling proteins, the pp32 family of nuclear phosphoproteins, several disease-associated gene products and other characterized and uncharacterized proteins.