The change of distribution of small GTP-binding proteins by GTPγS and its regulation by IgE receptor stimulation in α-toxin-permeabilized rat basophilic leukemia (RBL-2H3) cells

• Published in: Japanese Journal of Pharmacology 1992, Vol.58 (suppl.1), p.85-85
• Main Authors: Youichi Fukuda, Tomoyuki Uekusa, Atsushi Nakagawa, Masaatsu K. Uchida, Kazuhiko Oishi
• Format: Article
• Language: Japanese
• ISSN: 0021-5198

The details of the molecular mechanisms involved in the late stages of the exocytosis are largely unknown. Recently, it was shown that rab3A, one of small GTP-binding protein, dissociated from synaptic vesicles during exocytosis (Fischer von Mollard et al., Nature 349, 79-81, 1991). This result suggested that membrane fusion-fission events are regulated by cycling of small GTP-binding proteins between membrane-bound and free states. We previously reported that several small GTP-binding proteins associated to plasma membrane and secretory granules of RBL-2H3 cells. The present study was undertaken to investigate the interaction of small GTP-binding proteins with plasma membrane in permeabilized RBL-2H3 cells. RBL-2H3 cells were permeabilized by Staphylococcal α-toxin which forms pores of 2-3 nm in plasma membranes. The treatment of the cells with a stable GTP analogue guanosine 5'-「γ-thio」triphosphate (GTPγS) caused the dissociation of the small GTP-binding proteins from the plasma membrane, but the stimulation of IgE receptors by DNP-HSA did not. Moreover, the GTPγS-induced dissociation was blocked by the IgE receptor stimulation. These results indicate that the receptor stimulation facilitates the association of the small GTP-binding proteins to the plasma membrane. The contribution of the receptor-coupled regulation to secretion in the permeabilized cells is under investigation.