Journal: Journal of Virology
Article Title: Cyclin-Dependent Kinase 2 Phosphorylates S/T-P Sites in the Hepadnavirus Core Protein C-Terminal Domain and Is Incorporated into Viral Capsids
Figure Lengend Snippet: Endogenous kinase reactions with virion-derived HBV capsids. HBV capsids were released from virions purified from the medium of HBV-transfected HepG2 cells by NP-40 treatment. One control aliquot was removed, and the remaining virion-derived capsids were digested by proteinase K. The untreated (lane 1) or proteinase K-treated (lanes 2 to 5), virion-derived capsids (ca. 6 ng per reaction) were phosphorylated by the encapsidated kinase in endogenous kinase reactions in the presence of the indicated kinase inhibitors (lanes 3 to 5) or DMSO control (lane 2). Kinase inhibitors used included CDK2 inhibitor III (lane 3, 250 μM, 500× IC 50 for CDK2), roscovitine (lane 4, 250 μM, 350× IC 50 for CDK2), and Bisindo (lane 3, 5 μM, 500× IC 50 for PKC). An equal amount of proteinase K alone was also loaded as an additional control (lane 6). In parallel, 6 ng (lane 7) or 12 ng (lane 8) of cytoplasmic HBV capsids from HepG2 cells (also treated with proteinase K; see Materials and Methods) were subjected to the endogenous kinase reaction. Half of each reaction product was resolved by agarose gel electrophoresis to visualize capsid particles (top), and proteinase K inhibitor was added to the other half to terminate the digestion before boiling in SDS sample buffer and resolving by SDS-PAGE to visualize the total core protein (bottom). The gels were dried, and labeled capsids or core proteins were detected by autoradiography. *, unknown labeled species. CA, capsids; C, core protein; PK, proteinase K; IC, intracellular.
Article Snippet: When proteinase K-treated capsids were resolved by SDS-PAGE, the proteinase K digestion was stopped by adding proteinase K inhibitor (Calbiochem) to 1 mM (final concentration) and incubating the sample at room temperature for 10 min ( ).
Techniques: Derivative Assay, Purification, Transfection, Agarose Gel Electrophoresis, SDS Page, Labeling, Autoradiography