Sensitive immunodetection of pseudo-mutant conformation of p53 protein in human cells using immune complex with protein A conjugates.

The p53 tumor suppressor protein is a biologically very important molecule. In addition to its central relevance in cancer, its function as an inducer of cell cycle checkpoint and apoptosis may be important in a number of cellular stress responses. However, studies of p53 interactions with other proteins have been hampered in large part by the low abundance of normal p53 in cells. Moreover, the detection of p53 in immune complexes is complicated by the presence of comigrating immunoglobulin chains in SDS-polyacrylamide gels. The method described herein, which utilizes protein A-horseradish peroxidase conjugates, in combination with chemiluminescent detection methods, allows ready sensitive detection of p53 protein in immune complexes with little interference by comigrating immunoglobulin chains. Using this method, pseudo-mutant form as one of confusing conformations of p53 mutant protein was able to be identified with the criteria as high basal level of p53 expression and immunodetection with PAb1620 in human cells.