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Featured Citations

Convergent MurJ flippase inhibition by phage lysis proteins. Li YE, Antillon SF et al. Nature. 2026 Apr 30;652(8112):1274–1280.

Mechanism of co-transcriptional cap snatching by influenza polymerase. Rotsch AH, Li D et al. Nature. 2026 Apr 30;652(8112):1281–1288.

Integrase anchors viral RNA to the HIV-1 capsid interior. Singer MR, Li Z et al. Nature. 2026 Apr 23;652(8111):1068–1075.

The E3 ubiquitin ligase mechanism specifying targeted microRNA degradation. Farnung J, Slobodyanyuk E et al. Nature. 2026 Apr 16;652(8110):784–793.

Non-equilibrium snapshots of ligand efficacy at the μ-opioid receptor. Robertson MJ, Modak A et al. Nature. 2026 Apr 16;652(8110):794–802.

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News

December 25, 2025

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The RBVI wishes you a safe and happy holiday season! See our 2025 card and the gallery of previous cards back to 1985.

December 16, 2025

The ChimeraX 1.11 production release is available! See the change log for what's new.

November 21, 2025

The ChimeraX 1.11 release candidate is available – please try it and report any issues. See the change log for what's new. This will be the last release to support Red Hat Enterprise Linux 8 and its derivatives.

Previous news...

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UCSF ChimeraX

UCSF ChimeraX (or simply ChimeraX) is the next-generation molecular visualization program from the Resource for Biocomputing, Visualization, and Informatics (RBVI), following UCSF Chimera. ChimeraX can be downloaded free of charge for academic, government, nonprofit, and personal use. Commercial users, please see ChimeraX commercial licensing.

ChimeraX is developed with support from National Institutes of Health R01-GM129325.

Bluesky logo ChimeraX on Bluesky: @chimerax.ucsf.edu

Feature Highlight

heterodimer modeling screenshot

Multichain Comparative Modeling

Modeller Comparative is an interface to Modeller for comparative (“homology”) modeling of proteins and protein complexes.

The example shows modeling the human (shades of blue) from the mouse (brown and tan) complex of programmed death-1 (PD-1) with its ligand PD-L2, PDB 3bp5.

Comparative modeling requires a template structure and a target-template sequence alignment for each unique chain. The sequences of human PD-1 and PD-L2 targets were fetched from UniProt and associated with the corresponding chains in the template structure, see model-pdl-setup.cxc. (Pairwise or multiple sequence alignments could have been used, but in this case, the template structure was simply associated with the target sequence.) Sequence-structure association shows mismatches in the Sequence Viewer: pink boxes for sequence differences between mouse and human, and gray outlines around the parts missing from the structure.

Three models were made with with default settings (other than the number of models), and the best-scoring model is shown. Two positions where sequence differences change the interfacial H-bonds are displayed.

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Example Image

potassium channel

Potassium Channel-Calmodulin Complex

KCNQ1 is the pore-forming subunit of a cardiac potassium channel. It binds to calmodulin, and mutations in either of these proteins can cause congenital long QT syndrome, a dangerous propensity for irregular heartbeats. In the image, a structure of the KCNQ1/calmodulin complex (PDB 5vms) has been assembled into the native tetrameric form with the sym command. The view is from the cytoplasmic side, with KCNQ1 shown as surfaces, calmodulin as cartoons, and calcium ions as balls. A pastel palette from ColorBrewer has been used to color the surfaces, darkened with color modify for the cartoons, and “rotated” 45° in hue for the ions. See the command file colormod.cxc.

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