Purification of functional recombinant YY1 expressed in Sf9 insect cells

We expressed a gene for YY1, the multifunctional mammalian transcription factor, with a recombinant baculovirus in insect cells and obtained high levels of protein in cell lysates. A simple and efficient purification method was developed. In the final step, we used DNA affinity chromatography with concatermerized sequence derived from the upstream region of the B19 parvovirus P6 promoter, which has strong affinity for YY1. Approximately 1.8 mg of highly purified YY1 was obtained from 10(9) Sf9 cells. Highly purified YY1 behaved as authentic YY1 on electrophoretic mobility shift assays and in enhancing transcription from the P6 promoter. YY1 produced in a baculovirus system should prove useful for in vitro transcription assays of YY1 and related regulatory proteins.