The tau lesions in Pick's disease (and also in the brain of this particular patient) show a remarkable feature: they are Bielschowsky-positive and Gallyas-negative; in addition tau is phosphorylated at many epitopes but 12E8 (Ser/Ser).
Furthermore, RPA2 was shown to be phosphorylated at Ser, Ser, Ser, Thr, Ser, Ser and Ser by ATM and DNA-PK in vitro, many of which coincide with those phosphorylated in vivo in response to DNA damage [ 13, 36, 38– 41].
Yeast 26S proteasome has been shown to be phosphorylated at low stoichiometry (Wu et al., 2011).
STX1 can be phosphorylated at residues other than Ser14.
P01233 can theoretically be phosphorylated at three sites.
This ability to respond rapidly is supported by the RNA Pol II that is phosphorylated at serine 5 of its CTD, which is enriched at many PRC1/PRC2 targets in ES cells.
Although MeCP2 is expressed in many adult tissues it is phosphorylated at Ser421 almost exclusively in the adult brain (Zhou et al., 2006), suggesting that phosphorylation of MeCP2 at this residue is required for homeostatic brain functions.
STAT3 contains an SH2 domain, and it is phosphorylated at tyrosine 705 (Tyr) and serine 727 (Ser) in response to many cytokines and growth factors [ 5].
Thus, for example, in many cells most catalytic subunit is complexed to regulatory subunit and inactive but is phosphorylated at T197.
Furthermore, in ZnO NP exposed cells, p53 protein was phosphorylated at Ser33 and Ser46 sites known to be phosphorylated by p38.
