Recorded 18 November 2022. Maya Topf of the University of Hamburg presents "Refinement and validation of atomic models in cryo-EM maps using TEMPy2" at IPAM's Cryo-Electron Microscopy and Beyond Workshop. Abstract: As the resolutions of cryo-EM reconstructions of macromolecular assemblies are being improved, there is a need for better refinement methods of atomic models in medium-to-high resolutions. There is also a strong need for robust approaches for model assessment. Here, we present the current capabilities of our software TEMPy2 to refine and assess atomic models in cryo-EM maps. By representing the atomic positions as components of a mixture model, their variances as B-factors, and a model ensemble description, we significantly improve the fit to the map. We apply the software to refine and assess a large benchmark of 366 assemblies from EMDB (at 1.8-7.1 A° resolution) and CASP14 cryo-EM targets (2.1-3.8 A° resolution). We also show that our approach can provide newly-modelled regions in EMDB deposited maps by combining it with AlphaFold-Multimer. Learn more online at: http://www.ipam.ucla.edu/programs/workshops/workshop-iii-cryo-electron-microscopy-and-beyond/?tab=schedule