These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Exocytosis in mast cells by basic secretagogues: evidence for direct activation of GTP-binding proteins.
    Author: Aridor M, Traub LM, Sagi-Eisenberg R.
    Journal: J Cell Biol; 1990 Sep; 111(3):909-17. PubMed ID: 1697300.
    Abstract:
    Histamine release induced by the introduction of a nonhydrolyzable analogue of GTP, GTP-gamma-S, into ATP-permeabilized mast cells, is associated with phosphoinositide breakdown, as evidenced by the production of phosphatidic acid (PA) in a neomycin-sensitive process. The dependency of both PA formation and histamine secretion on GTP-gamma-S concentrations is bell shaped. Whereas concentrations of up to 0.1 mM GTP-gamma-S stimulate both processes, at higher concentrations the cells' responsiveness is inhibited. At a concentration of 1 mM, GTP-gamma-S self-inhibits both PA formation and histamine secretion. Inhibition of secretion can, however, be overcome by the basic secretagogues compound 48/80 and mastoparan that in suboptimal doses synergize with 1 mM GTP-gamma-S to potentiate secretion. Secretion under these conditions is not accompanied by PA formation and is resistant both to depletion of Ca2+ from internal stores and to pertussis toxin (PtX) treatment. In addition, 48/80, like mastoparan, is capable of directly stimulating the GTPase activity of G-proteins in a cell-free system. Together, our results are consistent with a model in which the continuous activation of a phosphoinositide-hydrolyzing phospholipase C (PLC) by a stimulatory G-protein suffices to trigger histamine secretion. Basic secretagogues of mast cells, such as compound 48/80 and mastoparan, are capable of inducing secretion in a mechanism that bypasses PLC by directly activating a G-protein that is presumably located downstream from PLC (GE). Thereby, these secretagogues induce histamine secretion in a receptor-independent manner.
    [Abstract] [Full Text] [Related] [New Search]