title: rab3-peptide stimulates exocytosis from mast cells via a pertussis toxin-sensitive mechanism.
abstract: Synthetic peptides of the putative effector domain of members of the rab3 gene family of small GTP-binding proteins have been shown to have potent actions on vesicular transport and exocytosis [1,2]. Here, we use similar rab3-effector domain peptides to study their role in intracellular signalling in mast cells. We find that rab3-like peptides stimulate exocytosis and decrease cyclic 3',5'-AMP levels in these cells when applied extracellularly. Cells pretreated with pertussis toxin (PtX) to selectively uncouple alpha i/alpha o type G proteins from their biological activators, however, did not respond to rab3 peptides. rab3-like peptides also induce a Ca2+ transient in mast cells. These observations provide evidence for functional coupling between an effector domain peptide sequence of rab3 protein and a PtX-sensitive G protein substrate.
authors.affiliation: Department of Neurobiology, AFRC, Babraham Institute, Cambridge, UK.
authors.forename: G J
authors.initials: GJ
authors.lastname: Law
authors.forename: A J
authors.initials: AJ
authors.lastname: Northrop
authors.forename: W T
authors.initials: WT
authors.lastname: Mason
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000502:physiology*; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology; D037342:Pertussis Toxin; D051381:Rats; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*; D014862:Wasp Venoms / Q000494:pharmacology; D020692:rab3 GTP-Binding Proteins
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D010566:Virulence Factors, Bordetella; D014862:Wasp Venoms; C083869:rab3AL peptide; C037500:mastoparan; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins