The human concentrative and equilibrative nucleoside transporter families, SLC28 and SLC29

Mol Aspects Med. Apr-Jun 2013;34(2-3):529-47. doi: 10.1016/j.mam.2012.05.007.


Nucleoside transport in humans is mediated by members of two unrelated protein families, the SLC28 family of cation-linked concentrative nucleoside transporters (CNTs) and the SLC29 family of energy-independent, equilibrative nucleoside transporters (ENTs). These families contain three and four members, respectively, which differ both in the stoichiometry of cation coupling and in permeant selectivity. Together, they play key roles in nucleoside and nucleobase uptake for salvage pathways of nucleotide synthesis. Moreover, they facilitate cellular uptake of several nucleoside and nucleobase drugs used in cancer chemotherapy and treatment of viral infections. Thus, the transporter content of target cells can represent a key determinant of the response to treatment. In addition, by regulating the concentration of adenosine available to cell surface receptors, nucleoside transporters modulate many physiological processes ranging from neurotransmission to cardiovascular activity. This review describes the molecular and functional properties of the two transporter families, with a particular focus on their physiological roles in humans and relevance to disease treatment.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adenosine / metabolism
  • Brain / metabolism
  • Cations / metabolism
  • Equilibrative Nucleoside Transport Proteins / genetics*
  • Equilibrative Nucleoside Transport Proteins / metabolism
  • Equilibrative Nucleoside Transport Proteins / physiology*
  • Humans
  • Intestinal Mucosa / metabolism
  • Kidney / metabolism
  • Liver / metabolism
  • Membrane Transport Proteins / genetics*
  • Membrane Transport Proteins / metabolism
  • Membrane Transport Proteins / physiology*
  • Models, Biological
  • Models, Molecular*
  • Molecular Structure
  • Multigene Family*
  • Phylogeny
  • Polymorphism, Single Nucleotide / genetics
  • Protein Conformation*
  • Species Specificity


  • Cations
  • Equilibrative Nucleoside Transport Proteins
  • Membrane Transport Proteins
  • cif nucleoside transporter
  • Adenosine