Membrane topology distinguishes a subfamily of the ATP-binding cassette (ABC) transporters

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A group of ATP-binding cassette (ABC) transporters, including the yeast cadmium transporter (YCF1), the mammalian multidrug resistance-associated protein (MRP), the multi-specific organic anion transporter and its congener (MOAT and EBCR), as well as the sulfonylurea receptor (SUR), group into a subfamily by sequence comparison. We suggest that these MRP-related proteins are also characterized by a special, common membrane topology pattern. The most studied ABC transporters, the cystic fibrosis transmembrane conductance regulator (CFTR) and the multidrug resistance (MDR) proteins, were shown to contain a tandem repeat of six transmembrane helices, each set followed by an ATP-binding domain. According to the present study, in contrast to various membrane topology predictions proposed for the different MRP-related proteins, they all seem to have a CFTR/MDR-like core structure, and an additional, large, N-terminal hydrophobic region. This latter domain is predicted to contain 4-6 (most probably 5) transmembrane helices, and is occasionally glycosylated on the cell surface. Since all the MRP-related transporters were shown to interact with anionic compounds, the N-terminal membrane-bound domain may have a key role in these interactions.

Original languageEnglish
Pages (from-to)1-3
Number of pages3
JournalFEBS letters
Issue number1
Publication statusPublished - febr. 3 1997


ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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