Extraordinary pleiotropy of protein kinase CK2 revealed by weblogo phosphoproteome analysis

A weblogo has been generated from the sequences surrounding 433 Ser/Thr protein residues whose phosphorylation by protein kinase CK2 had been previously validated (“bona fide” CK2 phosphosites). This has been compared to the weblogo extracted from 2275 putative CK2 phosphosites displaying the motif pS/pT-x1-x2-D/E/pS (where x1 ≠ P) present in the human phosphoElm database including 10 899 naturally occurring phosphosites. The two weblogos are strikingly similar supporting the notion that indeed the 2275 putative sites (accounting for 20.9% of the whole phosphoproteome they belong to), or at least the great majority of these are generated by CK2. This conclusion has been corroborated by the random validation of 8 of such putative CK2 sites (belonging to 5 different proteins) as real targets of CK2 in vitro and/or in cells, leading to the inclusion into the repertoire of bona fide CK2 targets of 5 new entries, namely: oxidative stress-responsive kinase-1, anthrax toxin receptor 1, hepatoma derived growth factor, EpsinR and BCL2/adenovirus E1B 19 kDa protein-interacting protein 3-like.