Coloring by Sequence Conservation

Atomic structures, including cartoons and molecular surfaces, can be colored by the conservation in an associated multiple sequence alignment. The figure shows a structure of the β₂-adrenergic receptor signaling complex (PDB 3sn6) with receptor cartoon colored blue→white→red from least conserved to most conserved. The β₂-adrenergic receptor is a member of the class A G-protein-coupled receptor superfamily. Conservation was calculated from a superfamily alignment from PASS2 using the entropy-based measure from AL2CO (included with ChimeraX courtesy of Pei and Grishin). The sequence alignment and step-by-step instructions for making this image are given in the Coloring by Sequence Conservation tutorial.

Calmodulin and Target Peptide

Calmodulin (CaM) acts as a calcium sensor. When its four Ca++ sites are fully occupied, it binds and modulates the activity of various downstream proteins, including CaM-dependent protein kinase I (CaMKI). Here, a complex between CaM and its target peptide from CaMKI (PDB 1mxe) is shown with cartoons, a transparent molecular surface, silhouette outlines, and light soft ambient occlusion. (If you prefer a less smudgy/rustic appearance, try using light gentle instead.) For image setup other than positioning, see the command file cam.cxc.

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