CHARACTERIZATION OF A DNA-BINDING PHOSPHOPROTEIN FROM VACCINIA VIRUS-REPLICATION COMPLEX

The DNA-protein complex which forms in the cytoplasm of HeLa cells during the course of vaccinia virus infection contains a single DNA-binding phosphoprotein, termed FP11. This phosphoprotein has been purified to near homogeneity by chromatography on denatured DNA-cellulose. Phosphoprotein FP11 has an apparent molecular weight of 34,000, as determined by electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate. High-voltage paper electrophoresis following acid hydrolysis reveals that the polypeptide contains phosphothreonine but not phosphoserine. The in vivo phosphorylation occurs at a minimum of four distinct phosphothreonine residues. FP11 is an acidic protein with an isoelectric point lying in the pH region 5.2-5.5. © 1978.