Mastoparan, a peptide toxin from wasp venom, mimics receptors by activating GTP-binding regulatory proteins (G proteins)

T. Higashijima, S. Uzu, T. Nakajima, E. M. Ross

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Abstract

Mastoparan, a peptide toxin from wasp venom, is a nonspecific secretagogue. We show here that mastoparan increases the GTPase activity and the rate of nucleotide binding of several purified GTP-binding regulatory proteins (G proteins) whose function is to couple cell-surface receptors to intracellular mediators. Mastoparan accelerated guanosine-5'-(3-O-thio-triphosphate binding and consequent G protein activation in part by promoting the dissociation of bound GDP, the mechanism by which receptors regulate G proteins. ADP-ribosylation by pertussis toxin, which uncouples receptors from G proteins, selectively inhibited mastoparan-stimulated activation. Like receptors, mastoparan was more potent if the G protein was reconstituted in phospholipid vesicles and was active at micromolar concentrations of Mg2+. The structure of mastoparan in a lipid bilayer is similar to that predicted for a cationic intracellular loop of G protein-coupled receptors. Mastoparan thus displays a novel mode of toxicity by acting directly on G proteins to mimic the role normally played by agonist-liganded receptors.

Original languageEnglish (US)
Pages (from-to)6491-6494
Number of pages4
JournalJournal of Biological Chemistry
Volume263
Issue number14
StatePublished - Jan 1 1988

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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