Details

Autor(en) / Beteiligte

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

Titel

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

Ist Teil von

• The Journal of biological chemistry, 1988-05, Vol.263 (14), p.6491-6494

Ort / Verlag

Bethesda, MD: Elsevier Inc

Erscheinungsjahr

1988

Quelle

MEDLINE

Beschreibungen/Notizen

• 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-thiotriphosphate 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.