caa a22 4500 528785745 20190713030954.0 cr unu---uuuuu 180924s2016 xx s 000 0 eng 10.3929/ethz-b-000118667 doi 10.1038/ncomms12100 doi (ETHRESEARCH)oai:www.research-collection.ethz.ch:20.500.11850/118667 Structural basis of transcobalamin recognition by human CD320 receptor [Elektronische Daten] [Amer Alam, Jae-Sung Woo, Jennifer Schmitz, Bernadette Prinz, Katharina Root, Fan Chen, Joël S. Bloch, Renato; id_orcid 0000-0001-5211-4358 Zenobi, Kaspar P. Locher] Nat Commun Open access ethresearch Cellular uptake of vitamin B12 (cobalamin) requires capture of transcobalamin (TC) from the plasma by CD320, a ubiquitous cell surface receptor of the LDLR family. Here we present the crystal structure of human holo-TC in complex with the extracellular domain of CD320, visualizing the structural basis of the TC-CD320 interaction. The observed interaction chemistry can rationalize the high affinity of CD320 for TC and lack of haptocorrin binding. The in vitro affinity and complex stability of TC-CD320 were quantitated using a solid-phase binding assay and thermostability analysis. Stable complexes with TC were also observed for the disease-causing CD320ΔE88 mutant and for the isolated LDLR-A2 domain. We also determined the structure of the TC-CD320ΔE88 complex, which revealed only minor changes compared with the wild-type complex. Finally, we demonstrate significantly reduced in vitro affinity of TC for CD320 at low pH, recapitulating the proposed ligand release during the endocytic pathway. Creative Commons Attribution 4.0 International http://creativecommons.org/licenses/by/4.0 ethresearch Alam Amer joint author Woo Jae-Sung joint author Schmitz Jennifer joint author Prinz Bernadette joint author Root Katharina joint author Chen Fan joint author Bloch Joël S. joint author Zenobi Renato; id_orcid 0000-0001-5211-4358 joint author Locher Kaspar P. joint author Nature Communications London : Nature Publishing Group 7, p. 12100 2041-1723 http://hdl.handle.net/20.500.11850/118667 text/html WWW-Backlink auf das Repository (Open access) 1 Journal Article ethresearch ETHRESEARCH 856 40 http://hdl.handle.net/20.500.11850/118667 text/html WWW-Backlink auf das Repository (Open access) ETHRESEARCH 700 1- Alam Amer joint author ETHRESEARCH 700 1- Woo Jae-Sung joint author ETHRESEARCH 700 1- Schmitz Jennifer joint author ETHRESEARCH 700 1- Prinz Bernadette joint author ETHRESEARCH 700 1- Root Katharina joint author ETHRESEARCH 700 1- Chen Fan joint author ETHRESEARCH 700 1- Bloch Joël S. joint author ETHRESEARCH 700 1- Zenobi Renato; id_orcid 0000-0001-5211-4358 joint author ETHRESEARCH 700 1- Locher Kaspar P. joint author ETHRESEARCH 773 0- Nature Communications London : Nature Publishing Group 7, p. 12100 2041-1723 BK010053 XK010053 XK010000 ETHRESEARCH ETHRESEARCH ETHRESEARCH Journal Article Open access