9ZUN

Structural insights into the exosite-mediated activation of Factor IX by Factor XIa using cryoEM

Summary for 9ZUN

• Entry DOI: 10.2210/pdb9zun/pdb
• Related: 9ZQY 9ZTK 9ZUB
• EMDB information: 74822
• Descriptor: Coagulation factor XIa heavy chain, Coagulation factor XIa light chain, Coagulation factor IX, ... (5 entities in total)
• Functional Keywords: coagulation, intrinsic pathway, complex, hemophilia, factor ix, factor xia, blood clotting
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 3
• Total formula weight: 116312.12

Authors

Mohammed, B.M. (deposition date: 2025-12-24, release date: 2026-09-09)

Primary citation

Mohammed, B.M.,Deavila, S.,Friet, T.,Dattilio, I.
Structural insights into the exosite-mediated activation of Factor IX by Factor XIa using cryo-EM.
J.Thromb.Haemost., 2026

PubMed Abstract: Factor XI (FXI) occupies a unique and clinically significant niche, bridging the tissue factor-driven and contact-driven coagulation pathways. Irrespective of the trigger, activated factor XI (FXIa) contributes to clotting by activating factor IX (FIX). Biochemical studies established that this reaction requires the membrane-binding FIX-Gla domain to engage an exosite on the FXIa Apple 3 (A3) domain, that only become available upon FXI activation. Structural data for FXIa, FIX, FIXaβ, and the FXIa:FIX complex are lacking; current understanding relies on zymogen FXI crystal structures and homology modeling of FXIa after kallikrein.

PubMed: 42628751
DOI: 10.1016/j.jtha.2026.08.015

Experimental method

ELECTRON MICROSCOPY (3.55 Å)