ArticlePharmaceutical research2003
Preliminary investigation into the expression of proton-coupled oligopeptide transporters in neural retina and retinal pigment epithelium (RPE): lack of functional activity in RPE plasma membranes.
Article in Pharmaceutical research, 2003. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 11 papers.
What it found
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Who cites it
11 citing papers in PubMed, 45 citations in OpenAlex.
- Oligopeptide/Histidine Transporter PHT1 and PHT2 - Function, Regulation, and Pathophysiological Implications Specifically in Immunoregulation.Pharmaceutical research · 2023Review
- Di- and tripeptide transport in vertebrates: the contribution of teleost fish models.Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology · 2017Review
- Immunohistochemical and functional characterization of peptide, organic cation, neutral and basic amino acid, and monocarboxylate drug transporters in human ocular tissues.Drug metabolism and disposition: the biological fate of chemicals · 2013Article
- Transporter-targeted lipid prodrugs of cyclic cidofovir: a potential approach for the treatment of cytomegalovirus retinitis.Journal of pharmaceutical sciences · 2012Article
- Prodrug strategies in ocular drug delivery.Medicinal chemistry (Shariqah (United Arab Emirates)) · 2012Review
- THE EVALUATION OF PEPTIDE/HISTIDINE TRANSPORTER 1 (PHT1) FUNCTION: UPTAKE KINETICS UTILIZING A COS-7 STABLY TRANSFECTED CELL LINE.Revista mexicana de ciencias farmaceutica · 2011Article
- Peptide transporter 1 is responsible for intestinal uptake of the dipeptide glycylsarcosine: studies in everted jejunal rings from wild-type and Pept1 null mice.Journal of pharmaceutical sciences · 2011Article
- Effect of HEPES buffer on the uptake and transport of P-glycoprotein substrates and large neutral amino acids.Molecular pharmaceutics · 2010Article
- Recent perspectives in ocular drug delivery.Pharmaceutical research · 2009Review
- Role and relevance of PEPT2 in drug disposition, dynamics, and toxicity.Drug metabolism and pharmacokinetics · 2008Review
- Role of PEPT2 in the choroid plexus uptake of glycylsarcosine and 5-aminolevulinic acid: studies in wild-type and null mice.Pharmaceutical research · 2004Article
Corrections and comments
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Authors and funding
6 authors at 1 institution in 1 country.
Funding
Abstract
purposeTo determine the expression and functional activity of proton-coupled oligopeptide transporters (POT) in retinal pigment epithelial (RPE) cells.
methodsRT-PCR was used to probe the presence of POT mRNA in freshly isolated bovine RPE (BRPE) and human RPE (HRPE) cells, a human RPE cell line (ARPE-19), and human and bovine neural retina. [14C]GlySar uptake was used to characterize POT activity in cultured ARPE-19 cells and freshly isolated BRPE cell sheet suspensions.
resultsPHT1 mRNA was expressed in BRPE, HRPE, ARPE-19, and bovine and human neural retina. In contrast, PEPT2 and PHT2 were expressed only in bovine and human retina, and PEPT1 could not be detected. GlySar exhibited a linear uptake over 6 h at pH values of 6.0 and 7.4, with greater uptake at pH 7.4 (p < 0.01). GlySar uptake did not exhibit saturability (5-2000 microM) and was unchanged when studied in the presence of 1 mM L-histidine. In contrast, GlySar uptake was significantly decreased when studied at 4 degrees C or in the presence of endocytic inhibitors at 37 degrees C (p < 0.01). Studies in BRPE cell sheet suspensions validated the results obtained in ARPE-19 cells and strongly suggested the absence of POT on the apical and basolateral membranes of RPE.
conclusionsPHT1 mRNA is present in native bovine and human RPE and a human RPE cell line. However, the data argue against PHT1 being expressed on plasma membranes of RPE. Overall, GlySar appears to be taken up by RPE cells via a low-affinity, endocytic process.
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