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Twelve transmembrane helices form the functional core of mammalian MATE1
Author(s) -
Zhang Xiaohong,
He Xiao,
Baker Joseph,
Tama Florence,
Chang Geoffrey,
Wright Stephen
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.1099.2
Subject(s) - transmembrane domain , transmembrane protein , cytoplasm , biology , transporter , homology modeling , peptide sequence , membrane topology , amino acid , extracellular , chemistry , biochemistry , gene , enzyme , receptor
MATE1 and MATE2/2‐K, the mammalian organic cation/H + (OC/H + ) exchangers, are key players in renal and hepatic secretion of cationic drugs. They belong to a superfamily of transport proteins (Multidrug And Toxin Extruders) with 1000+ members. The x‐ray structure of the prototypic MATE family member, NorM from Vibrio cholera , shows a protein fold comprised of 12 transmembrane helices (TMHs), as predicted by hydropathy analysis of the majority of MATE transporters. However, the mammalian MATEs are predicted to have a C‐terminal 13 th TMH. Here we confirmed the presence of the 13 th TMH in mammalian MATE1. Whereas the C‐termini of epitope‐tagged, full length human, rabbit and mouse MATE1 were accessible to antibodies from the extracellular face of the membrane, truncation of these proteins at or near the junction between the 13 th TMH and the long cytoplasmic loop that precedes it resulted in proteins that (i) trafficked to the membrane, (ii) had a cytoplasmic C‐terminus, and (iii) supported substrate transport. The latter observation indicates that the functional ‘core structure’ of mammalian MATE consists of the first 12 TMHs, whereas the 13 th TMH is not necessary for essential function. Therefore, we used the x‐ray structure of NorM to develop a homology model of the 3D structure of hMATE1 that proved to be stable in Molecular Dynamic simulations when placed ( in silico ) in a hydrated phospholipid bilayer.