Volta Phase Plate Cryo-EM Structure of the Human Heterodimeric Amino Acid Transporter 4F2hc-LAT2

Int J Mol Sci. 2019 Feb 21;20(4):931. doi: 10.3390/ijms20040931.

Abstract

Heteromeric amino acid transporters (HATs) are protein complexes that catalyze the transport of amino acids across plasma membranes. HATs are composed of two subunits, a heavy and a light subunit, which belong to the solute carrier (SLC) families SLC3 and SLC7. The two subunits are linked by a conserved disulfide bridge. Several human diseases are associated with loss of function or overexpression of specific HATs making them drug targets. The human HAT 4F2hc-LAT2 (SLC3A2-SLC7A8) is specific for the transport of large neutral L-amino acids and specific amino acid-related compounds. Human 4F2hc-LAT2 can be functionally overexpressed in the methylotrophic yeast Pichia pastoris and pure recombinant protein purified. Here we present the first cryo-electron microscopy (cryo-EM) 3D-map of a HAT, i.e., of the human 4F2hc-LAT2 complex. The structure could be determined at ~13 Å resolution using direct electron detector and Volta phase plate technologies. The 3D-map displays two prominent densities of different sizes. The available X-ray structure of the 4F2hc ectodomain fitted nicely into the smaller density revealing the relative position of 4F2hc with respect to LAT2 and the membrane plane.

Keywords: 4F2hc; L-type amino acid transporter; LAT2; SLC3; SLC7; Volta phase plate; cryo-EM; direct electron detector; heteromeric amino acid transporter.

MeSH terms

  • Adaptor Proteins, Signal Transducing / chemistry*
  • Adaptor Proteins, Signal Transducing / metabolism
  • Cryoelectron Microscopy / instrumentation
  • Cryoelectron Microscopy / methods*
  • Fusion Regulatory Protein 1, Heavy Chain / chemistry*
  • Fusion Regulatory Protein 1, Heavy Chain / metabolism
  • Humans
  • Protein Domains
  • Protein Multimerization

Substances

  • Adaptor Proteins, Signal Transducing
  • Fusion Regulatory Protein 1, Heavy Chain
  • LAT2 protein, human
  • SLC3A2 protein, human