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Updated: Jun 28, 2026

Expression, Solubilization, and Purification of Eukaryotic Borate Transporters
Published on: March 7, 2019
Structure and molecular mechanism of a nucleobase-cation-symport-1 family transporter
Simone Weyand1, Tatsuro Shimamura, Shunsuke Yajima
1Membrane Protein Laboratory, Diamond Light Source Limited, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 0DE, UK.
Abstract:
The nucleobase-cation-symport-1 (NCS1) transporters are essential components of salvage pathways for nucleobases and related metabolites. Here, we report the 2.85-angstrom resolution structure of the NCS1 benzyl-hydantoin transporter, Mhp1, from Microbacterium liquefaciens. Mhp1 contains 12 transmembrane helices, 10 of which are arranged in two inverted repeats of five helices. The structures of the outward-facing open and substrate-bound occluded conformations were solved, showing how the outward-facing cavity closes upon binding of substrate. Comparisons with the leucine transporter LeuT(Aa) and the galactose transporter vSGLT reveal that the outward- and inward-facing cavities are symmetrically arranged on opposite sides of the membrane. The reciprocal opening and closing of these cavities is synchronized by the inverted repeat helices 3 and 8, providing the structural basis of the alternating access model for membrane transport.
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