Transcriptional inactivation of p53 by deletions and single amino acid changes in mouse mot-1 protein.

Mouse mortalin proteins, mot-1 and mot-2, differ by only two amino acid residues in their C-terminus. In previous studies we showed that they differ in their subcellular distributions and interactions with the tumor suppressor protein, p53. By using mot-1 deletion mutants and amino acid substitution constructs, we report here that inability of mot-1 to affect p53 activity in vivo is dependent on the presence of both of the unique mot-1 amino acids and all three of the predicted hsp70, EF hand, and leucine zipper motif regions. The two proteins and their single amino acid mutants showed different mobilities on SDS-polyacrylamide gel presenting an evidence for their different secondary structures. Taken together, the data suggest that each of the two differing amino acids between mot-1 and mot-2 is an important determinant of their secondary structures and in vivo activities. Copyright 2000 Academic Press.