Figure 2.

Model of human CK1α bound to NS5A peptide whose phosphoserine is topologically equivalent to arginine in substrate peptide bound to cAMP dependent kinase. Stereo figure showing modelled position of the side chain of phosphoserine 229 of NS5A in the same orientation as its topologically equivalent residue (an Arg) of the pseudosubstrate of cAPK (cAMP dependent kinase). This brings the side chain of phosphoserine 229 coloured in green unfavourably proximal to a like charged side chain of Asp 140 coloured in cyan. Therefore, the side chain of phosphoserine is unlikely to be oriented in the same way as the topologically equivalent Arg in the pseudosubstrate of cAMP dependent kinase. After the remodelling of the side chain of phosphoserine 229 it points towards the putative substrate interacting residues Arg 214, Lys 260, Gly 251 and makes favourable ionic interaction as shown in Figure 3.