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

@article{Flintoff2003TheRB,
  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},
  year={2003},
  volume={278},
  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… Expand
Analysis of the membrane topology for transmembrane domains 7-12 of the human reduced folate carrier by scanning cysteine accessibility methods.
TLDR
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. Expand
Localization of a Substrate Binding Domain of the Human Reduced Folate Carrier to Transmembrane Domain 11 by Radioaffinity Labeling and Cysteine-substituted Accessibility Methods*
TLDR
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. Expand
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*
TLDR
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. Expand
Restoration of Transport Activity by Co-expression of Human Reduced Folate Carrier Half-molecules in Transport-impaired K562 Cells
TLDR
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. Expand
Structure and function of the reduced folate carrier a paradigm of a major facilitator superfamily mammalian nutrient transporter.
TLDR
This article focuses on the biology of the membrane transport system termed the "reduced folate carrier" or RFC with a particular emphasis on RFC structure and function. Expand
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). TheExpand
Functional analysis of altered reduced folate carrier sequence changes identified in osteosarcomas.
TLDR
Three alterations, Ser46Asn, Ser4Pro and Gly259Trp, while able to complement the carrier null line, conferred some degree of resistance to Mtx via a decreased rate of transport (Vmax). Expand
Biological Role, Properties, and Therapeutic Applications of the Reduced Folate Carrier (RFC-SLC19A1) and the Proton-Coupled Folate Transporter (PCFT-SLC46A1)
The mechanisms by which folates are transported across cell membranes have been an area of research interest for nearly five decades. Major transport systems include the facilitative carriers, theExpand
Expansion of the Major Facilitator Superfamily (MFS) to include novel transporters as well as transmembrane-acting enzymes.
TLDR
Nine previously unclassified protein families in the Transporter Classification Database are assigned to the Major Facilitator Superfamily based on multiple criteria and bioinformatic methodologies. Expand
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. InExpand
...
1
2
...

References

SHOWING 1-10 OF 35 REFERENCES
Characterization of a cysteine-less human reduced folate carrier: localization of a substrate-binding domain by cysteine-scanning mutagenesis and cysteine accessibility methods.
The human reduced folate carrier (hRFC) mediates the transport of reduced folates and classical anti-folates into mammalian cells. Whereas the functionally important domains in hRFC are poorlyExpand
Membrane Topology of a Cysteine-less Mutant of Human P-glycoprotein (*)
TLDR
It was found that 8 of 15 cysteine residues introduced into P-glycoprotein-A52 could be biotinylated, which is consistent with the model of P- glycoprotein, which predicts six transmembrane segments in each of the two homologous halves of the molecule. Expand
Identification of lysine-411 in the human reduced folate carrier as an important determinant of substrate selectivity and carrier function by systematic site-directed mutagenesis.
TLDR
A functionally important role for a basic amino acid at position 411 was implied by the increased MTX transport for wild-type hRFC over the K411 mutant hRFCs, and the highly selective uptake of 5-CHO-H(4)PteGlu over MTX for K411R-hRFC. Expand
Cytoplasmic domains of the reduced folate carrier are essential for trafficking, but not function.
TLDR
Although these cytoplasmic domains do not appear to be absolutely essential for substrate transport, each one is important for biogenesis and localization. Expand
Functional Role of Arginine 373 in Substrate Translocation by the Reduced Folate Carrier*
TLDR
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. Expand
Analysis of membrane topology of the human reduced folate carrier protein by hemagglutinin epitope insertion and scanning glycosylation insertion mutagenesis.
TLDR
To establish the RFC membrane topology, a hemagglutinin (HA) epitope was inserted into the individual predicted intracellular and extracellular loops, and results raise the possibility of an alternative membraneTopology for TMDs 9-12. Expand
Discrimination among reduced folates and methotrexate as transport substrates by a phenylalanine substitution for serine within the predicted eighth transmembrane domain of the reduced folate carrier.
TLDR
The data indicate that residues in the predicted eighth transmembrane domain of RFC1 can play an important role in the selectivity of folate binding and the mobility of the carrier-substrate complex. Expand
Role of the C-terminus and the long cytoplasmic loop in reduced folate carrier expression and function.
The reduced folate carrier (RFC1), a member of the major facilitative superfamily, generates uphill transport of folates into cells through an exchange mechanism with intracellular organic anions.Expand
Topology of the Region Surrounding Glu681 of Human AE1 Protein, the Erythrocyte Anion Exchanger*
TLDR
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. Expand
Topological and Functional Analysis of the Human Reduced Folate Carrier by Hemagglutinin Epitope Insertion*
TLDR
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. Expand
...
1
2
3
4
...