Uridine Binding and Transportability Determinants of Human Concentrative Nucleoside Transporters
| Autor: | Jing Zhang, Carol E. Cass, Ireneusz Nowak, Stephen A. Baldwin, Edward Karpinski, Lars P. C. Nielsen, Kyla M. Smith, Morris J. Robins, James D. Young, Tracey Tackaberry, Frank Visser |
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| Rok vydání: | 2005 |
| Předmět: |
Protein family
Stereochemistry Voltage clamp Xenopus law.invention chemistry.chemical_compound law Membrane Transport Modulators Humans Uridine DNA Primers Pharmacology Base Sequence biology Membrane Transport Proteins Transporter biology.organism_classification Recombinant Proteins Yeast Biochemistry chemistry Recombinant DNA Molecular Medicine Nucleoside Protein Binding |
| Zdroj: | Molecular Pharmacology. 68:830-839 |
| ISSN: | 1521-0111 0026-895X |
| DOI: | 10.1124/mol.105.012187 |
| Popis: | Human concentrative nucleoside transporters 1, 2, and 3 (hCNT1, hCNT2, and hCNT3) exhibit different functional characteristics, and a better understanding of their permeant selectivities is critical for development of nucleoside analog drugs with optimal pharmacokinetic properties. In this study, the sensitivity of a high-throughput yeast expression system used previously for hCNT1 and hCNT3 was improved and used to characterize determinants for interaction of uridine (Urd) with hCNT2. The observed changes of binding energy between hCNT2 and different Urd analogs suggested that it interacts with C(3′)-OH, C(5′)-OH, and N(3)-H of Urd. The C(2′) and C(5) regions of Urd played minor but significant roles for Urd-hCNT2 binding, possibly through Van der Waals interactions. Because the yeast assay only provided information about potential transportability, the permeant selectivities of recombinant hCNT1, hCNT2, and hCNT3 produced in Xenopus laevis oocytes were investigated using a two-electrode voltage clamp assay. hCNT1-mediated transport was sensitive to modifications of the N(3), C(3′), and C(5′) positions of Urd. hCNT2 showed some tolerance for transporting Urd analogs with C(2′) or C(5) modifications, little tolerance for N(3) modifications, and no tolerance for any modifications at C(3′) or C(5′) of Urd. Although hCNT3 was sensitive to C(3′) modifications, it transported a broad range of variously substituted Urd analogs. The transportability profiles identified in this study, which reflected the binding profiles well, should prove useful in the development of anticancer and antiviral therapies with nucleoside drugs that are permeants of members of the hCNT protein family. |
| Databáze: | OpenAIRE |
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