Scavenger receptor CD163 multimerises to allow uptake of diverse ligands

Abstract CD163 is an archetypal scavenger receptor and mediates detoxification of free haemoglobin. Release of haemoglobin from lysed erythrocytes causes oxidative tissue and organ damage. Detoxification involves haemoglobin binding to the abundant serum protein haptoglobin, followed by CD163-mediat...

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Main Authors: Richard X. Zhou, Matthew K. Higgins
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-62054-9
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author Richard X. Zhou
Matthew K. Higgins
author_facet Richard X. Zhou
Matthew K. Higgins
author_sort Richard X. Zhou
collection DOAJ
description Abstract CD163 is an archetypal scavenger receptor and mediates detoxification of free haemoglobin. Release of haemoglobin from lysed erythrocytes causes oxidative tissue and organ damage. Detoxification involves haemoglobin binding to the abundant serum protein haptoglobin, followed by CD163-mediated uptake of stoichiometrically diverse haptoglobin-haemoglobin complexes into macrophages for degradation. We show that CD163 adopts dimeric and trimeric assemblies due to calcium-mediated interactions within a membrane-associated base. Arms protrude from this base and create a ligand-binding site. Flexibility within the base, coupled with multiple small ligand-binding surfaces on each arm, allow the receptor to mould around its ligands, resulting in promiscuous uptake of ligands with different structures and stoichiometries. Monomeric CD163 lacks this ability to internalise lower-avidity ligands. Arms from adjacent protomers can also self-associate, blocking ligand-binding surfaces in an autoinhibited state. Therefore, through calcium-dependent multimer formation and flexible ligand binding, CD163 scavenges ligands with different structures and avidities, mediating haemoglobin detoxification.
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spelling doaj-art-02c6cebe28ef46ac94ecf8943ff3a6ce2025-08-20T03:46:28ZengNature PortfolioNature Communications2041-17232025-07-0116111110.1038/s41467-025-62054-9Scavenger receptor CD163 multimerises to allow uptake of diverse ligandsRichard X. Zhou0Matthew K. Higgins1Department of Biochemistry, University of Oxford, South Parks RoadDepartment of Biochemistry, University of Oxford, South Parks RoadAbstract CD163 is an archetypal scavenger receptor and mediates detoxification of free haemoglobin. Release of haemoglobin from lysed erythrocytes causes oxidative tissue and organ damage. Detoxification involves haemoglobin binding to the abundant serum protein haptoglobin, followed by CD163-mediated uptake of stoichiometrically diverse haptoglobin-haemoglobin complexes into macrophages for degradation. We show that CD163 adopts dimeric and trimeric assemblies due to calcium-mediated interactions within a membrane-associated base. Arms protrude from this base and create a ligand-binding site. Flexibility within the base, coupled with multiple small ligand-binding surfaces on each arm, allow the receptor to mould around its ligands, resulting in promiscuous uptake of ligands with different structures and stoichiometries. Monomeric CD163 lacks this ability to internalise lower-avidity ligands. Arms from adjacent protomers can also self-associate, blocking ligand-binding surfaces in an autoinhibited state. Therefore, through calcium-dependent multimer formation and flexible ligand binding, CD163 scavenges ligands with different structures and avidities, mediating haemoglobin detoxification.https://doi.org/10.1038/s41467-025-62054-9
spellingShingle Richard X. Zhou
Matthew K. Higgins
Scavenger receptor CD163 multimerises to allow uptake of diverse ligands
Nature Communications
title Scavenger receptor CD163 multimerises to allow uptake of diverse ligands
title_full Scavenger receptor CD163 multimerises to allow uptake of diverse ligands
title_fullStr Scavenger receptor CD163 multimerises to allow uptake of diverse ligands
title_full_unstemmed Scavenger receptor CD163 multimerises to allow uptake of diverse ligands
title_short Scavenger receptor CD163 multimerises to allow uptake of diverse ligands
title_sort scavenger receptor cd163 multimerises to allow uptake of diverse ligands
url https://doi.org/10.1038/s41467-025-62054-9
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