A novel hPepT1 stably transfected cell line: establishing a correlation between expression and function

Mol Pharm. 2004 Mar-Apr;1(2):136-44. doi: 10.1021/mp034011l.


Stably transfected MDCK/hPepT1-V5&His clonal cell lines expressing varying levels of epitope-tagged hPepT1 protein were established to quantify the relationship between transgene hPepT1 expression levels and its functional kinetics in facilitating peptide and peptide-like drug uptake and transport in vitro. The hPepT1 sequence was amplified from Caco-2 cell mRNA, inserted into the pcDNA3.1 -V5&His TOPO plasmid, and transfected into MDCK cells. Transgene protein levels were quantified by Western Blot analysis utilizing a standard curve generated with a positive control protein containing a V5&His epitope. Three clones expressing different levels of the hPepT1 fusion protein (low, medium, and high) were selected for the functional characterization with [14C]Gly-Sar and [3H]carnosine. The MDCK/hPepT1 cells expressed a novel hPepT1/epitope tag protein with an apparent molecular mass of 110 kDa. The [14C]Gly-Sar uptake in the transfected cells was sodium-independent and pH-dependent, demonstrating enhanced uptake, the rate of which increased significantly from the weakly to strongly expressing hPepT1 MDCK/hPepT1 -V5&His clones as compared to the mock cell line at pH 6.0. The uptake and permeability of [14C]Gly-Sar and [3H]carnosine demonstrated a direct correlation between the hPepT1 level of expression, uptake, and transport capabilities. Molecular and functional characterization of the MDCK/hPepT1-V5&His cell line confirmed a directly proportional relationship between Vmax and Papp versus the molar levels of hPepT1 transgene expression. This stably transfected hPepT1 cell line may serve as a useful in vitro model for screening and quantifying peptide and peptide-like drug transport as a function of hPepT1 expression in drug discovery.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Biological Transport
  • Cell Line
  • Cell Line, Tumor
  • DNA Primers
  • Dipeptides / metabolism
  • Dogs
  • Drug Carriers
  • Humans
  • Kidney
  • Membrane Proteins / metabolism
  • Peptide Transporter 1
  • Polymerase Chain Reaction
  • Recombinant Proteins / metabolism
  • Symporters / genetics*
  • Symporters / metabolism*
  • Transfection


  • DNA Primers
  • Dipeptides
  • Drug Carriers
  • Membrane Proteins
  • Peptide Transporter 1
  • Recombinant Proteins
  • SLC15A1 protein, human
  • Symporters