Functional coupling between a bafilomycin A1-sensitive proton pump and a probenecid-sensitive folate transporter in human placental choriocarcinoma cells

Puttur D Prasad, Virendra B. Mahesh, Frederick H. Leibach, Vadivel Ganapathy

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The mechanism of transport of 5-methyltetrahydrofolate, the predominant form of folate in human blood, was investigated in JAR human placental choriocarcinoma cells. Northern analysis revealed the presence of the folate receptor mRNA in these cells. Accumulation of 5-methyltetrahydrofolate in these cells was saturable and inhibited by other folate analogs. The transport of 5-methyltetrahydrofolate into the cytoplasm was decreased by the anion transport inhibitors probenecid and 4,4′-diisothiocyanostilbene 2,2′-disulfonic acid. The cytosolic transport was dependent on a transmembrane H+ gradient because NH4Cl and chloroquine which alkalinize acidic compartments in the cell and protonophores which dissipate transmembrane H+ gradients inhibited the transport. The inhibitors of receptor-mediated endocytosis, monodansylcadaverine and bacitracin, had no effect on the cytosolic transport nor on the accumulation. Bafilomycin A1, a specific inhibitor of the vacuolar type (V-type) H+-pump, caused a significant reduction in the cytosolic transport of 5-methyltetrahydrofolate, without affecting the binding of the vitamin to its membrane bound receptor. It is concluded that (a) the JAR cells transport 5-methyltetrahydrofolate via a specific probenecid-sensitive folate transporter, (b) the transporter is driven by a transmembrane H+ gradient, and (c) the H+ gradient involved in this process is generated by a bafilomycin A1-sensitive V-type H+-pump present in the plasma membrane. The results strongly suggest that the transport of folate in these cells occurs by potocytosis involving a functional coupling between the folate receptor, the folate transporter and the H+ pump.

Original languageEnglish (US)
Pages (from-to)309-314
Number of pages6
JournalBBA - Molecular Cell Research
Volume1222
Issue number2
DOIs
StatePublished - Jun 30 1994

Fingerprint

Folic Acid Transporters
Probenecid
Proton Pumps
Choriocarcinoma
Folic Acid
Bacitracin
Chloroquine
Endocytosis
Vitamins
Anions
bafilomycin A1
Cytoplasm
Cell Membrane
5-methyltetrahydrofolate
Messenger RNA
Acids
Membranes

Keywords

  • (Choriocarcinoma cell)
  • Folate receptor
  • Folate/hydroxyl antiport
  • Potocytosis
  • Proton gradient
  • Proton pump

ASJC Scopus subject areas

  • Biophysics
  • Cell Biology
  • Molecular Biology

Cite this

Functional coupling between a bafilomycin A1-sensitive proton pump and a probenecid-sensitive folate transporter in human placental choriocarcinoma cells. / Prasad, Puttur D; Mahesh, Virendra B.; Leibach, Frederick H.; Ganapathy, Vadivel.

In: BBA - Molecular Cell Research, Vol. 1222, No. 2, 30.06.1994, p. 309-314.

Research output: Contribution to journalArticle

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