A community-wide data processing challenge for cryo-electron microscopy.

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Sign up for email notifications for challenge announcements here.

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Join the challenge discussions space on GitHub here.

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About

Cryo-electron microscopy (cryo-EM) has revolutionized structural biology by enabling high-resolution visualization of dynamic biomolecular assemblies. However, a central challenge remains: developing robust computational methods to model different forms of structural heterogeneity—including continuous motions, discrete states, and compositional variations—and to accurately estimate population distributions.

To encourage the development and benchmarking of heterogeneous reconstruction algorithms and workflows, we invite the cryo-EM community to analyze three new curated experimental and synthetic datasets:

  1. Compositional Heterogeneity
  2. Conformational Heterogeneity
  3. Pose Entanglement

Participants will be invited to the CCP-EM CAHRA Review Workshop in September 2026. If you are interested in participating, please sign up for email notifications and join our discussions space. Please share this with others who may be interested. We hope you’ll join us for this year’s challenge!

Timeline

Challenge announced July 25, 2025
Datasets released, submissions open November 1, 2025
Webinar November 14, 2025
12:00 PM EST
*Recording and slides.*
Preliminary submissions close* March 14, 2026
Final submissions close June 1, 2026
Results announced July 2026
CCP-EM CAHRA Review Workshop September 14-16, 2026
*Details.*

*Optional submissions received by the preliminary deadline will receive feedback and initial evaluation results before the final deadline.

Datasets

We encourage participants to review both the datasets and submission forms before downloading and processing the data.

01 Compositional Heterogeneity

02 Conformational Heterogeneity

03 Pose Entanglement

Resources