title: Farnesylcysteine, a constituent of the alpha and beta subunits of rabbit skeletal muscle phosphorylase kinase: localization by conversion to S-ethylcysteine and by tandem mass spectrometry.
abstract: The primary structure of the alpha and beta subunits of phosphorylase kinase reveals that both proteins contain a carboxyl-terminal CA1A2X motif (where C is cysteine, A1 and A2 are aliphatic amino acids, and X is an uncharged amino acid), the recognition signal for a protein polyisoprenyltransferase. The product, a polyisoprenylated cysteine, can be detected by phenylthiocarbamoylamino acid analysis and by microsequencing following conversion to S-ethylcysteine. Mass spectrometry confirms a covalently linked farnesyl residue in both subunits. Tandem mass spectrometry localizes these modifications at the cysteine residues present in the carboxyl-terminal CAMQ and CLVS sequences of the alpha and beta subunits, respectively. Membrane association of phosphorylase kinase, probably mediated by these farnesyl residues, is discussed.
authors.affiliation: Abteilung für Biochemie Supramolekularer Systeme, Ruhr-Universität Bochum, Federal Republic of Germany.
authors.forename: L M
authors.initials: LM
authors.lastname: Heilmeyer
authors.forename: M
authors.initials: M
authors.lastname: Serwe
authors.forename: C
authors.initials: C
authors.lastname: Weber
authors.forename: J
authors.initials: J
authors.lastname: Metzger
authors.forename: E
authors.initials: E
authors.lastname: Hoffmann-Posorske
authors.forename: H E
authors.initials: HE
authors.lastname: Meyer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009132:Muscles / Q000201:enzymology; D010446:Peptide Fragments / Q000737:chemistry; D010764:Phosphorylase Kinase / Q000737:chemistry*; D017368:Protein Prenylation; D011817:Rabbits
chemical_list: D010446:Peptide Fragments; C057785:S-farnesylcysteine; C026826:S-ethylcysteine; D010764:Phosphorylase Kinase; D003545:Cysteine