title: Measurement of relative amounts of phospho- and dephospho-B-50(GAP-43) peptides by fast atom bombardment-mass spectrometry.
abstract: The biological role of phosphoproteins depends upon their degree of phosphorylation in vivo. Methods currently available to measure the degree of phosphorylation of a protein involve indirect procedures to detect the 32P-phosphate incorporation. We report here a direct method to measure relative amounts of phospho- and dephospho-forms of peptides based upon a mass spectrometric technique. The intensities of the molecular ions corresponding to the two forms of the peptides are proportional to their relative amounts. This is demonstrated for a peptide fragment of the protein B-50(GAP-43) and for kemptide, respectively substrates for protein kinases C and A, and demonstrates the applicability of fast atom bombardment-mass spectrometry to quantitate peptides bearing post-translational modifications.
authors.affiliation: Institute of Pharmacological Sciences, University of Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Di Luca
authors.forename: P N
authors.initials: PN
authors.lastname: de Graan
authors.forename: L
authors.initials: L
authors.lastname: De Angelis
authors.forename: W H
authors.initials: WH
authors.lastname: Gispen
authors.forename: F
authors.initials: F
authors.lastname: Cattabeni
mesh_terms: D000595:Amino Acid Sequence; D005069:Evaluation Studies as Topic; D019922:GAP-43 Protein; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism*; D010750:Phosphoproteins / Q000032:analysis* / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D016339:Spectrometry, Mass, Fast Atom Bombardment / Q000379:methods*
chemical_list: D019922:GAP-43 Protein; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D010750:Phosphoproteins; C037642:kemptide; D011494:Protein Kinases