Δ160p53 is a novel N-terminal p53 isoform encoded by Δ133p53 transcript

p53 gene expresses several protein isoforms modulating p53-mediated responses through regulation of gene expression. Here, we identify a novel p53 isoform, Delta 160p53, lacking the first 159 residues. By knockdown experiments and site-directed mutagenesis, we show that Delta 160p53 is encoded by Delta 133p53 transcript using ATG160 as translational initiation site. This hypothesis is supported by endogenous expression of Delta 160p53 in U2OS, T47D and K562 cells, the latter ones carrying a premature stop codon that impairs p53 and Delta 133p53 protein expression but not the one of Delta 160p53. Overall, these results show that the Delta 133p53 transcript generates two different p53 isoforms, Delta 133p53 and Delta 160p53. (C) 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.