Structures of proteinase 3 and the CD177 receptor complex reveal a major autoantibody epitope

Journal article

Granulomatosis with polyangiitis is a life-threatening systemic vasculitis, characterised by anti-neutrophil cytoplasmic autoantibodies (ANCA) most commonly against proteinase 3 (PR3), a protease expressed intracellularly and on the surface of neutrophils. Most cell surface PR3 is bound to the receptor CD177; however, the molecular mechanism of the interactions is not well understood. Here, we present crystal structures of CD177 in complex with PR3 and unliganded CD177. We describe a mainly hydrophobic binding interface between PR3 and CD177, involving the first two Ly6/uPAR (LU) domains of CD177. These form a globular structure which is connected to downstream domains via a flexible linker. Using a panel of PR3-ANCA-positive patient samples, we show that a significant proportion of ANCAs target the CD177-binding site of PR3 in these samples. Structure-guided mutation of the CD177-binding site on PR3 is effective in reducing PR3-ANCA binding. The results demonstrate that the CD177-binding surface of PR3 harbours a major PR3-ANCA epitope, and that the extent of binding to this surface varies between different patients.

Authors: Zheng-Gérard, C; Joha, J; Carrasquero, M; El Omari, K; Lowe, E

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer
• Journal: EMBO Reports
• Pages: 1-27
• Publication date: 2026-02-17
• Acceptance date: 2026-01-30
• DOI: 10.1038/s44319-026-00716-5
• EISSN: 1469-3178
• ISSN: 1469-221X
• Language: English
• Keywords: Epitope mapping; Proteinase K; Autoantibody; Mutation; Cytoplasm; Receptor; Proteinase 3; Epitope; Binding site