Structure of the Human Cation-Independent Mannose 6-Phosphate/IGF2 Receptor Domains 7-11 Uncovers the Mannose 6-Phosphate Binding Site of Domain 9

Structure. 2020 Dec 1;28(12):1300-1312.e5. doi: 10.1016/j.str.2020.08.002. Epub 2020 Sep 1.

Abstract

The cation-independent mannose 6-phosphate (M6P)/Insulin-like growth factor-2 receptor (CI-MPR/IGF2R) is an ∼300 kDa transmembrane protein responsible for trafficking M6P-tagged lysosomal hydrolases and internalizing IGF2. The extracellular region of the CI-MPR has 15 homologous domains, including M6P-binding domains (D) 3, 5, 9, and 15 and IGF2-binding domain 11. We have focused on solving the first structures of human D7-10 within two multi-domain constructs, D9-10 and D7-11, and provide the first high-resolution description of the high-affinity M6P-binding D9. Moreover, D9 stabilizes a well-defined hub formed by D7-11 whereby two penta-domains intertwine to form a dimeric helical-type coil via an N-glycan bridge on D9. Remarkably the D7-11 structure matches an IGF2-bound state of the receptor, suggesting this may be an intrinsically stable conformation at neutral pH. Interdomain clusters of histidine and proline residues may impart receptor rigidity and play a role in structural transitions at low pH.

Keywords: CI-MPR; IGF2R; P-type lectin; X-ray crystallography; domain 9; mannose 6-phosphate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Humans
  • Hydrogen-Ion Concentration
  • Mannosephosphates / chemistry
  • Mannosephosphates / metabolism
  • Molecular Docking Simulation
  • Protein Binding
  • Protein Multimerization
  • Receptor, IGF Type 2 / chemistry*
  • Receptor, IGF Type 2 / metabolism

Substances

  • IGF2R protein, human
  • Mannosephosphates
  • Receptor, IGF Type 2
  • mannose-6-phosphate