Fig 2.

PKA phosphorylates HPV8 E2 protein at the serine 253 residue. CV-1 cell lines carrying control vector plasmid pMEP4 or plasmid expressing 240-255-CTD E2 protein were either untreated or pretreated for 2 h with the PKA inhibitor H-89 at 10 μM or the PKA enhancer forskolin at 10 μM or CTX at 100 ng/ml, followed by E2 induction for 3 h. (A) RIPA cell extracts were prepared, and equivalent amounts of total proteins were immunoprecipitated with M2 anti-FLAG antibody beads. Phosphorylated E2 protein was detected using phospho-RRXS motif-specific antibody, followed by reblotting for total E2 protein using rabbit anti-FLAG antibody. (B) Quantitative representation of the relative amounts of phosphorylated E2 protein to total E2 protein observed by immunoblotting in panel A. UT, untreated. Error bars represent standard deviations from three experimental repeats.