GTP-induced fusion of isolated pancreatic microsomal vesicles is increased by acidification of the vesicle lumen.
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GTP-induced fusion of isolated pancreatic microsomal vesicles is increased by acidification of the vesicle lumen. / Hampe, Wolfgang; Zimmermann, P; Schulz, I.
In: FEBS LETT, Vol. 271, No. 1-2, 1-2, 1990, p. 62-66.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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T1 - GTP-induced fusion of isolated pancreatic microsomal vesicles is increased by acidification of the vesicle lumen.
AU - Hampe, Wolfgang
AU - Zimmermann, P
AU - Schulz, I
PY - 1990
Y1 - 1990
N2 - Using the 'fusogen' polyethyleneglycol (PEG), Dawson et al. have concluded that both guanosine triphosphate (GTP)-induced calcium efflux and the enhancement of IP3-promoted calcium release from rat liver microsomal vesicles could be attributed to a GTP-dependent vesicle fusion. We have studied GTP-induced fusion of microsomal vesicles from rat exocrine pancreas using light scatter and fluorescence dequenching methods. In the presence of PEG (3%), GTP (10 microM) induced a decrease in light scatter and an increase in fluorescence in the fluorescence dequenching assay (GTP-effect) indicating fusion of the vesicles. Guanosine 5'-O-(3-thiotriphosphate) (10 microM) had no effect on its own and inhibited the GTP-induced signals. Preincubation of the vesicles with adenosine triphosphate (ATP) (4 mM) increased the GTP-effect by 80%, whereas bafilomycin B1, a specific inhibitor of vacuolar type H(+)-ATPases, and the protonophore CCCP (10 microM) inhibited only the ATP-dependent part of the GTP-effect. Inhibitors of the vacuolar type H(+)-ATPase, which are also SH-alkylating reagents such as N-ethylmaleimid (100 microM) and the tyrosine-, cysteine- and lysine-reactive reagent 7-chloro-4-nitrobenz-2-exa-1,3-diazole (10 microM), abolished the GTP-effect in the absence or presence of ATP. We conclude that GTP induces fusion of pancreatic microsomes which is increased by an H+ gradient established by a vacuolar type H(+)-ATPase.
AB - Using the 'fusogen' polyethyleneglycol (PEG), Dawson et al. have concluded that both guanosine triphosphate (GTP)-induced calcium efflux and the enhancement of IP3-promoted calcium release from rat liver microsomal vesicles could be attributed to a GTP-dependent vesicle fusion. We have studied GTP-induced fusion of microsomal vesicles from rat exocrine pancreas using light scatter and fluorescence dequenching methods. In the presence of PEG (3%), GTP (10 microM) induced a decrease in light scatter and an increase in fluorescence in the fluorescence dequenching assay (GTP-effect) indicating fusion of the vesicles. Guanosine 5'-O-(3-thiotriphosphate) (10 microM) had no effect on its own and inhibited the GTP-induced signals. Preincubation of the vesicles with adenosine triphosphate (ATP) (4 mM) increased the GTP-effect by 80%, whereas bafilomycin B1, a specific inhibitor of vacuolar type H(+)-ATPases, and the protonophore CCCP (10 microM) inhibited only the ATP-dependent part of the GTP-effect. Inhibitors of the vacuolar type H(+)-ATPase, which are also SH-alkylating reagents such as N-ethylmaleimid (100 microM) and the tyrosine-, cysteine- and lysine-reactive reagent 7-chloro-4-nitrobenz-2-exa-1,3-diazole (10 microM), abolished the GTP-effect in the absence or presence of ATP. We conclude that GTP induces fusion of pancreatic microsomes which is increased by an H+ gradient established by a vacuolar type H(+)-ATPase.
M3 - SCORING: Zeitschriftenaufsatz
VL - 271
SP - 62
EP - 66
JO - FEBS LETT
JF - FEBS LETT
SN - 0014-5793
IS - 1-2
M1 - 1-2
ER -