Medical College of Wisconsin
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Intracellular trafficking and membrane targeting mechanisms of the human reduced folate carrier in Mammalian epithelial cells. J Biol Chem 2002 Sep 06;277(36):33325-33 PMID: 12087110

Abstract

The major pathway for cellular uptake of the water-soluble 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 NH(2)- 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.

Author List

Marchant JS, Subramanian VS, Parker I, Said HM

Author

Jonathan S. Marchant PhD Chair, Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Biological Transport
Carrier Proteins
Cell Line
Cell Membrane
Cells, Cultured
Cytoplasm
Cytoskeleton
DNA, Complementary
Dogs
Epithelial Cells
Flow Cytometry
Green Fluorescent Proteins
Humans
Luminescent Proteins
Membrane Transport Proteins
Microscopy, Confocal
Microscopy, Video
Microtubules
Open Reading Frames
Peptides
Protein Structure, Tertiary
Protein Transport
Recombinant Fusion Proteins
Temperature
Time Factors
Transfection



View this publication's entry at the Pubmed website PMID: 12087110
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