Intracellular trafficking and membrane targeting mechanisms of the human reduced folate carrier in mammalian epithelial cells

Jonathan S Marchant, Veedamali S. Subramanian, Ian Parker, Hamid M. Said

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

The major pathway for cellular uptake of the watersoluble vitamin folic acid in mammalian cells is via a plasma membrane protein known as the reduced folate carrier (RFC). The molecular determinants that dictate plasma membrane expression of RFC as well as the cellular mechanisms that deliver RFC to the cell surface remain poorly defined. Therefore, we designed a series of fusion proteins of the human RFC (hRFC) with green fluorescent protein to image the targeting and trafficking dynamics of hRFC in living epithelial cells. We show that, in contrast to many other nutrient transporters, the molecular determinants that dictate hRFC plasma membrane expression reside within the hydrophobic backbone of the polypeptide and not within the cytoplasmic NH2- or COOH-terminal domains of the protein. Further, the integrity of the hRFC backbone is critical for export of the polypeptide from the endoplasmic reticulum to the cell surface. This trafficking is critically dependent on intact microtubules because microtubule disruption inhibits motility of hRFC-containing vesicles as well as final expression of hRFC in the plasma membrane. For the first time, these data define the mechanisms that control the intracellular trafficking and cell surface localization of hRFC within mammalian epithelia.

Original languageEnglish (US)
Pages (from-to)33325-33333
Number of pages9
JournalJournal of Biological Chemistry
Volume277
Issue number36
DOIs
StatePublished - Sep 6 2002

Bibliographical note

Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.

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