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August, 2026
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Bassem M. Mohammed: New Cryo-EM Study Reveals How Factor XIa Activates Factor IX
Aug 28, 2026, 11:56

Bassem M. Mohammed: New Cryo-EM Study Reveals How Factor XIa Activates Factor IX

Bassem M. Mohammed, Assistant Professor at Saint Louis University School of Medicine, shared a post on LinkedIn about a recent article he and his colleagues co-authored, published in JTH, adding:

“Proud to share that the latest study from our new lab, ‘Structural insights into the exosite-mediated activation of Factor IX by Factor XIa using cryo-EM,’ is officially out in the Journal of Thrombosis and Haemostasis (JTH)!

This project was a true team effort.

A huge shout-out to Samantha Deavila, Tristan Friet, and Isabella Dattilio for their incredible work on protein purification and generation, with special recognition to Isabella Dattilio for kicking off the recombinant protein production and tagging work in the Lab!

We are also deeply grateful to Editor Ton Lisman and the reviewers for their wonderful guidance throughout the publication process.

Using cryo-EM, our lab successfully captured the first high-resolution structures of FXIa bound to its physiological substrate, Factor IX (FIX), and the activated product (FIXab).

Crowning decades of biochemical work, modeling, and biophysical studies, these structures provide direct visual evidence of how the calcium-dependent FIX Gla-domain docks onto the FXIa-A3 exosite and reveal how the catalytic domain of FXIa pivots to accommodate and process the incoming substrate.

We are excited about how this structural template will open doors for designing selective allosteric antithrombotics targeting the contact pathway.”

Title: Structural insights into the exosite-mediated activation of Factor IX by Factor XIa using cryo-EM

Authors: Bassem M. Mohammed, Samantha Deavila, Tristan Friet, and Isabella Dattilio

Bassem M. Mohammed

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