Regulation of exocytosis by the small GTP-binding protein Rho in rat basophilic leukemia (RBL-2H3) cells.
1. We investigated the effect of Clostridium botulinum C3 ADP-ribosyltransferase upon beta-hexosaminidase release induced by various stimuli from streptolysin-O (0.5-1 U/ml)-permeabilized rat basophilic leukemia (RBL-2H3) cells. 2. The C3 transferase inhibited beta-hexosaminidase release induced by Ca2+ or by guanosine-5'-(3-thiotriphosphate) (GTP gamma S) plus Ca2+. 3. The C3 transferase also inhibited beta-hexosaminidase release induced by stimulating high affinity IgE and m3 muscarinic acetylcholine receptors. 4. The substrate for the C3 transferase was present in cytosol of RBL-2H3 cells, indicating the presence of rho p21. About 60% of the total cellular substrate protein remained within the cells permeabilized by 1 U/ml of streptolysin-O. 5. The protein rho p21 appears to be regulated by several pathways and it may function as an integration point for exocytosis.
Yonei
S G
SG
Department of Molecular Pharmacology, Meiji College of Pharmacy, Tokyo, Japan.
Oishi
K
K
Uchida
M K
MK
D036002:ADP Ribose Transferases / Q000378:metabolism*; D000818:Animals; D001905:Botulinum Toxins; D002463:Cell Membrane Permeability; D003014:Clostridium botulinum / Q000201:enzymology; D005089:Exocytosis / Q000187:drug effects*; D019204:GTP-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D015471:Leukemia, Basophilic, Acute; D051381:Rats; D014407:Tumor Cells, Cultured; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism*; D020741:rho GTP-Binding Proteins
D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001619:beta-N-Acetylhexosaminidases; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins