Bovine prion protein as a modulator of protein kinase CK2

On the basis of far-Western blot and plasmon resonance (BIAcore) experiment s, we show here that recombinant bovine prion protein (bPrP) (25-242) stron gly interacts with the catalytic alpha/alpha' subunits of protein kinase CK 2 (also termed 'casein kinase 2'). This association leads to increased phos photransferase activity of CK2 alpha, tested on calmodulin or specific pept ides as substrate. We also show that bPrP counteracts the inhibition of cal modulin phosphorylation promoted by the regulatory beta subunits of CK2. A truncated form of bPrP encompassing the C-terminal domain (residues 105-242 ) interacts with CK2 but does not affect its catalytic activity. The opposi te is found with the N-terminal fragment of bPrP (residues 25-116), althoug h the stimulation of catalysis is less efficient than with full-size bPrP. These results disclose the potential of the PrP to modulate the activity of CK2, a pleiotropic protein kinase that is particularly abundant in the bra in.