Characterization of p53 protein expression in Jurkat cell lines expressing ZEBRA protein (Z+) and control cells (Z−).

B-lymphoblastoid Namalwa cells (NA) used as a positive control for detection of p53 protein. (A) p53 protein was detected by Western blotting using a polyclonal p53-specific anti-sera in nuclear protein extracts prepared from Z+ cells transiently transfected with p53W and p53C expression plasmids, but not in nuclear extracts from Z+ cells transfected with p53N expression plasmid or in nuclear extracts from Z− cells transfected with any p53 expression vectors. Levels of carboxyl terminus deleted p53 protein (53C) were significantly less than wild-type protein (53W) in Z+ cells, and the expected location of p53C protein is indicated (*). (B) p53 protein was not detected by Western blotting using a polyclonal p53-specific anti-sera in cytoplasmic-protein enriched hypotonic lysates of Z+ cells in the presence of transfected p53 expression plasmids with the possible exception of a small amount of p53N detected in both Z+ and Z− cell lysates (**). Hypotonic lysates used in this figure contained detectable ZEBRA protein (Figure 1D).