Association of cytokeratin p39 with DNA in intact Novikoff hepatoma cells.

The relationship between the rat tumor-associated cytokeratin p39 (Mr 39,000) and cellular DNA has been studied in intact cells. Using a DNA-protein crosslinking technique, incubation with cis-dichlorodiammineplatinum, we present evidence for the association of p39 with DNA in intact Novikoff ascites hepatoma cells. The cells were treated with cis-dichlorodiammineplatinum and solubilized in NaDodSO4-containing buffer, and the DNA was pelleted by high-speed centrifugation. By immunotransfer analysis, the cytokeratin was found in the DNA pellet of the crosslinked samples while absent from the controls. This result was further substantiated by CsCl density-gradient centrifugation. Collectively, these results suggest a cytokeratin-DNA association at the filament binding sites on or near the nuclear lamina.