ADP-ribosylation of transducin by islet-activating protein. Identification of asparagine as the site of ADP-ribosylation

D. R. Manning, B. A. Fraser, R. A. Kahn, A. G. Gilman

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


Islet-activating protein catalyzes the ADP-ribosylation of transducin, a guanine nucleotide-binding regulatory protein that mediates activation of a retinal cyclic GMP-selective phosphodiesterase. Radiolabel from [adenylate-32P]NAD+ was incorporated specifically into the α subunit of purified transducin. Maximal levels of incorporation approximated 0.8 mol of ADPribose/mol of transducin. A peptide containing the ADP-ribosyl moiety was purified from a tryptic digest of radiolableled transducin. This peptide was characterized by chemical and enzymatic procedures and by fast atom bombardment mass spectrometry. The primary structure of this peptide was Glu-Asn-Leu-Lys-Asn(ADP-ribose)-Gly-Leu-Phe. It is probable that the peptide originated from the carboxyl terminus of the α subunit and that the ADP-ribosyl moiety is attached by an N-glycosidic linkage to the asparagine residue. Transducin associated with retinal disc membranes is also ADP-ribosylated by cholera toxin. Cholera toxin and islet-activating protein sequentially catalyze the incorporation of 1.9 mol of ADP-ribose/mol of transducin, indicating two distinct sites of ADP-ribosylation within transducin.

Original languageEnglish (US)
Pages (from-to)749-756
Number of pages8
JournalJournal of Biological Chemistry
Issue number2
StatePublished - 1984

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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