Janin Plot

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A Janin plot generated by CING from chain A, Arginine residue number 18 in the protein Dynein Light Chain, (PDB ID 1y4o). The blue region show likely angle combinations for helical residues, while the yellow areas are for regions that are common to strand-like stretches. Some green background can be seen for residues that are in other types of regions.
A Janin plot generated by CING from chain A, Arginine residue number 18 in the protein Dynein Light Chain, (PDB ID 1y4o). The blue region show likely angle combinations for helical residues, while the yellow areas are for regions that are common to strand-like stretches. Some green background can be seen for residues that are in other types of regions.


A Janin plot is like the Ramachandran plot a way to visualize dihedral angles. Whereas the later relates the two backbone dihedral angles, this plot relates the first side chain dihedrals χ-1 against χ-2 for those amino acid residues in protein structure that have them. This is an important correlation that is different for the different amino acids and can depend on the secondary structure type (Helix, Sheet, etc.) that the residue is in. This plot, is named for J. Janin who studied these correlations in 1978.

[edit] References

  • Janin et al. Conformation of amino acid side-chains in proteins. J Mol Biol (1978) PMID 731698