The Region between Transmembrane Domains 1 and 2 of the Reduced Folate Carrier Forms Part of the Substrate-binding Pocket*

  title={The Region between Transmembrane Domains 1 and 2 of the Reduced Folate Carrier Forms Part of the Substrate-binding Pocket*},
  author={Wayne F. Flintoff and Frederick M. R. Williams and Heather Sadlish},
  journal={Journal of Biological Chemistry},
  pages={40867 - 40876}
A functional cysteine-less form of the hamster reduced folate carrier protein was generated by alanine replacement of the 14 cysteine residues. The predicted 12-transmembrane topology was examined by replacing selected amino acids, predicted to be exposed to the extracellular or cytosolic environments, with cysteines. The location of these cysteines was defined by their accessibility to biotin maleimide in the presence or absence of specific blocking agents. Amino acids predicted to be exposed… 

Analysis of the membrane topology for transmembrane domains 7-12 of the human reduced folate carrier by scanning cysteine accessibility methods.

Results strongly support a 12-TMD topology structure for the hRFC protein, which was introduced into the predicted extracellular or cytoplasmic loops of a fully functional cysteine-less hRFC expressed in transport impaired MtxRIIOua(R)2-4 Chinese hamster ovary cells.

Localization of a Substrate Binding Domain of the Human Reduced Folate Carrier to Transmembrane Domain 11 by Radioaffinity Labeling and Cysteine-substituted Accessibility Methods*

The results strongly suggest that residues within TMD 11 are likely critical structural and/or functional components of the putative hRFC transmembrane channel for anionic folate and anti-folate substrates.

Transmembrane Domains 4, 5, 7, 8, and 10 of the Human Reduced Folate Carrier Are Important Structural or Functional Components of the Transmembrane Channel for Folate Substrates*

These results implicate amino acids in T MDs 4, 5, 7, 8, 10, and 11, but not in TMDs 1, 2, 3, 6, 9, or 12, as important structural or functional components of the putative hydrophilic cavity for binding of anionic folate substrates.

Restoration of Transport Activity by Co-expression of Human Reduced Folate Carrier Half-molecules in Transport-impaired K562 Cells

It is demonstrated that a functional RFC can be reconstituted with RFC half-molecules and localize a critical substrate binding domain to within TMDs 7–12.

Human reduced folate carrier: translation of basic biology to cancer etiology and therapy

This review attempts to provide a comprehensive overview of the biology of the physiologically and pharmacologically important transport system termed the “reduced folate carrier” (RFC). The

Biological Role, Properties, and Therapeutic Applications of the Reduced Folate Carrier (RFC-SLC19A1) and the Proton-Coupled Folate Transporter (PCFT-SLC46A1)

This review focuses on the facilitative pathways of (anti)folate transport, including RFC and PCFT in relation to their molecular properties, and their physiological and pharmacological roles.

Expansion of the Major Facilitator Superfamily (MFS) to include novel transporters as well as transmembrane-acting enzymes.

Comparative molecular biological analysis of membrane transport genes in organisms

Comparative analyses of membrane transport genes revealed many differences in the features of transport homeostasis in eight diverse organisms, ranging from bacteria to animals and plants. In



Cytoplasmic domains of the reduced folate carrier are essential for trafficking, but not function.

Although these cytoplasmic domains do not appear to be absolutely essential for substrate transport, each one is important for biogenesis and localization.

Functional Role of Arginine 373 in Substrate Translocation by the Reduced Folate Carrier*

Cross-linking analysis of the Arg-373 residue demonstrates that it is within 6 Å of residue Glu-394 (TM11), providing the first definitive tertiary structural information for this protein.

Topology of the Region Surrounding Glu681 of Human AE1 Protein, the Erythrocyte Anion Exchanger*

The ability of mutants to mediate Cl−/ HCO3 − exchange in transfected HEK293 cells revealed that extracellular mutants, W648C, I650C, P652C, L655C, and F659C have an important role in transport.

Topological and Functional Analysis of the Human Reduced Folate Carrier by Hemagglutinin Epitope Insertion*

The membrane topology of the human reduced folate carrier protein was assessed by single insertions of the hemagglutinin epitope into nine sites of the protein, consistent with the 12-transmembrane topology predicted for this protein.

A Single Amino Acid Difference within the Folate Transporter Encoded by the Murine RFC-1 Gene Selectively Alters its Interaction with Folate Analogues

An analysis of topology, in addition to other considerations, suggests that the site of the amino acid difference found in the transporter from L1210 and S180 cells occurs within or near the binding site on the external plasma membrane surface.