title: Mass spectrometric analysis of novel phosphorylation sites in the TRPC4β channel.
abstract: BACKGROUND
  The transient receptor potential canonical (TRPC) channel 4β is a non-selective cation channel that is regulated by intracellular Ca(2+) and G protein-coupled receptors. Tyrosine phosphorylation of TRPC4β is important in mediating the activity and membrane expression of this channel protein. However, studies of TRPC4β Ser/Thr phosphorylation are lacking.
  
  
  METHODS
  To investigate the phosphorylation sites involved in regulating the diverse functions of TRPC4β in mammalian cells, we used nano-liquid chromatography/tandem mass spectrometry to identify key phosphorylation sites in TRPC4β that was immunopurified from HEK293 cells with monoclonal anti-TRPC4β antibody.
  
  
  RESULTS
  We identified four phosphorylation sites in the C-terminus of TRPC4β, none of which had been previously reported. Our data show that TRPC4β in mammalian cells is highly phosphorylated under basal conditions at multiple sites, and that a mass spectrometric proteomic technique combined with antibody-based affinity purification is an effective approach to define the phosphorylation sites of TRPC4β channels in mammalian cells.
  
  
  CONCLUSIONS
  These novel phosphorylation sites on TRPC4β may play a potential role in the phosphorylation-mediated regulation of TRPC4β channel activity and function in mammalian cells.
authors: Department of Physiology, and Biomedical Science Institute, Kyung Hee University School of Medicine, Seoul 130-701, South Korea.
authors: Ji Eun
authors: JE
authors: Lee
authors: Min-Young
authors: MY
authors: Song
authors: Seok Kyo
authors: SK
authors: Shin
authors: Seong Han
authors: SH
authors: Bae
authors: Kang-Sik
authors: KS
authors: Park
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002846:Chromatography, Affinity / Q000379:methods; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D050052:TRPC Cation Channels / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D050052:TRPC Cation Channels; C489571:TRPC4 ion channel