TY - JOUR
T1 - A vacuolar-type proton ATPase mediates acidification of plasmalemmal vesicles during potocytosis
AU - Mineo, Chieko
AU - Anderson, Richard G W
N1 - Funding Information:
We thank Dr. D. K. Stone for generously supplying us with the anti-70-kDa IgG and for critically reading the manuscript. We also are indebted to Dr. Eric Smart who developed the procedure for isolating caveolae from plasma membranes and Grace Liao for technical assistance. This project was supported by grants from the National Institutes of Health (HL 20948 and GM43169) and the Perot Family Foundation.
PY - 1996/5/1
Y1 - 1996/5/1
N2 - Previously we showed that the potocytosis of 5-methyltetrahydrofolate is dependent on the acidification of plasmalemmal vesicles created each time a caveolae closes off from the cell surface. We now report that bafilomycin A1, which is a specific inhibitor of the V-type proton ATPase, inhibits 5- methyltetrahydrofolate uptake into MA104 cells (ED50 = 150 nM). The inhibitory effect was reversed within 30 rain after removal of the drug from the cells. Bafilomycin A1 had no effect on the binding of folic acid to its receptor. A concentration of up to 200 nM bafilomycin A1 did not affect sequestration of folate receptors. Immunoblotting showed that the 70-kDa subunit of the V-type proton pump was localized to caveolae-rich fractions isolated from the plasma membrane of these cells. These results suggest that a V-type proton pump acidities the lumen of plasmalemmal vesicles during potocytosis.
AB - Previously we showed that the potocytosis of 5-methyltetrahydrofolate is dependent on the acidification of plasmalemmal vesicles created each time a caveolae closes off from the cell surface. We now report that bafilomycin A1, which is a specific inhibitor of the V-type proton ATPase, inhibits 5- methyltetrahydrofolate uptake into MA104 cells (ED50 = 150 nM). The inhibitory effect was reversed within 30 rain after removal of the drug from the cells. Bafilomycin A1 had no effect on the binding of folic acid to its receptor. A concentration of up to 200 nM bafilomycin A1 did not affect sequestration of folate receptors. Immunoblotting showed that the 70-kDa subunit of the V-type proton pump was localized to caveolae-rich fractions isolated from the plasma membrane of these cells. These results suggest that a V-type proton pump acidities the lumen of plasmalemmal vesicles during potocytosis.
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U2 - 10.1006/excr.1996.0133
DO - 10.1006/excr.1996.0133
M3 - Article
C2 - 8612700
AN - SCOPUS:0029876268
SN - 0014-4827
VL - 224
SP - 237
EP - 242
JO - Experimental Cell Research
JF - Experimental Cell Research
IS - 2
ER -