BioProject

Protein Ser/Thr kinase CK2 is involved in a myriad of cellular processes including cell growth and proliferation by phosphorylating hundreds of substrates, yet the regulation process of CK2 function is poorly understood. More...

Protein Ser/Thr kinase CK2 is involved in a myriad of cellular processes including cell growth and proliferation by phosphorylating hundreds of substrates, yet the regulation process of CK2 function is poorly understood. The CK2 catalytic subunit, CK2α, is modified by O-GlcNAc on Ser347 proximal to a Cdk1 phosphorylation site at Thr344 on the same protein. The substrate selectivity for protein kinase CK2 was examined by performing kinase assays on protein microarrays spotted with 17,000 human proteins. Semisynthetic CK2α proteins were prepared to contain an unmodified C-terminal tail, S-GlcNAc-Serine at S347, or Pfa (non-hyrdolyzeable phosphomimic) at T344. These semisynthetic proteins were used to determine if the posttranslational modifications on CK2 alpha modulate the substrate selectivity for this pleiotropic kinase. The different semisynthetic CK2α proteins were tested alone and in the presence of the regulatory subunit CK2β since it is known that the CK2α subunit is active both in its isolated state and in the heterotetrameric state formed in the presence of the regulatory beta subunit. The CK2β subunit has been shown to modulate CK2 activity with some substrates and not others. Overall design: In the study presented here, kinase assays were performed using three different semisynthetic CK2 alpha proteins: unmodified C-terminal tail; S-GlcNAc-Ser at 347; and Pfa (phosphomimic) at 344. The semisynthetic proteins were each tested alone and in the presence of the regualatory CK2 beta subunit. There were six different kinase conditions and each condition was performed in duplicate and one no kinase control was performed to eliminate autophorylated proteins. Less...