Two forms of the nuclear matrix-bound p53 protein in HEK293 cells.

Like many other transcription factors, the tumor suppressor protein p53 is bound to the nuclear matrix (NM). To study the interaction of p53 with the NM in more detail, we used alkaline and acidic extractions of NM proteins. It was found that there are two forms of p53, alkali- and acid-soluble, in NM of HEK293 cells and only one alkali-soluble form in NM of actinomycin D-treated MCF-7 cells. We suggest that distinct forms of p53 differ either in interactions with NM proteins or in their charges.