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 licensing.

ChimeraX is developed with support from National Institutes of Health R01-GM129325 and the Office of Cyber Infrastructure and Computational Biology, National Institute of Allergy and Infectious Diseases.

Feature Highlight

Coloring by Molecular Lipophilicity Potential

Molecular lipophilicity potential (MLP) can be calculated for a protein and displayed with surface coloring using the command mlp or the Molecule Display icon . The image shows the photosynthetic reaction center from a purple sulfur bacterium, with MLP coloring on the molecular surface and membrane boundaries from OPM (Orientations of Proteins in Membranes entry 1eys). Blue and red balls represent the cytoplasmic and periplasmic sides of the bacterial inner membrane, respectively. Parts of the L, M, and H chains span the membrane, whereas the cytochrome subunit sits on the periplasmic side, at the top. The surface coloring ranges from dark goldenrod for the most hydrophobic potentials, through white, to dark cyan for the most hydrophilic. Ligands including lipid, detergent, heme, and various other cofactors are shown as purple surfaces.

For image setup after the structure from OPM has been opened, see the command file mlp.cxc.

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Example Image

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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