Curved Helix Cylinders

Protein α-helices can be shown as curved-cylinder “tubes“ with the cartoon style command. Helix tube mode is an alternative to the standard spiraling ribbons, and both modes are fully integrated with coil and β-strand cartoons. The structure at left is an AMPA-subtype glutamate receptor bound to the antiepileptic drug perampanel (PDB 5l1f). The receptor is tetrameric, and each chain is rainbow color-coded from blue at the N-terminus to red at the C-terminus. Four molecules of perampanel (pink) are bound near the bottom, between the transmembrane domain and the rest of the receptor. For image setup other than orientation, see the command file ampar.cxc.

See also: Presets menu

B-factor Coloring

Atomic B-factor values are read from PDB and mmCIF input files and assigned as attributes that can be shown with coloring and used in atom specification. This example shows B-factor variation within a structure of the HIV-1 protease bound to an inhibitor (PDB 4hvp). For complete image setup, including positioning, color key, and label, see the command file bfactor.cxc.

Additional color key examples can be found in tutorials: Coloring by Electrostatic Potential, Coloring by Sequence Conservation

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