Does p53 protein mediate an apoptosis checkpoint?
If p53-mediated DNA repair is critical for maintaining genomic integrity, p53 and its related DNA repair function should be well conserved from bacteria to humans. However, p53 and newly discovered members of the p53 gene family are present only in multicellular organisms. While p73 and p63 family members bind to the p53 consensus (93,94), to date there are no reports of their capacity for non-sequence-specific binding, for example, to mismatched DNA. The p53 homolog in Drosophila is the most primitive relative of p53 identified so far. Drosophila p53 mediates DNA damage-induced apoptosis but not growth arrest, suggesting that the primitive function of p53 is to mediate apoptosis in genome maintenance (95 97). Eliminating cells with damaged DNA by apoptosis is vital for multicellular organisms to prevent genetic transformation (98). It is generally accepted that p53-mediated apoptosis and p53-induced cell cycle checkpoints are the two major mechanisms of p53 protein activity as a tumor
If p53-mediated DNA repair is critical for maintaining genomic integrity, p53 and its related DNA repair function should be well conserved from bacteria to humans. However, p53 and newly discovered members of the p53 gene family are present only in multicellular organisms. While p73 and p63 family members bind to the p53 consensus (93,94), to date there are no reports of their capacity for non-sequence-specific binding, for example, to mismatched DNA. The p53 homolog in Drosophila is the most primitive relative of p53 identified so far. Drosophila p53 mediates DNA damage-induced apoptosis but not growth arrest, suggesting that the primitive function of p53 is to mediate apoptosis in genome maintenance (95–97). Eliminating cells with damaged DNA by apoptosis is vital for multicellular organisms to prevent genetic transformation (98). It is generally accepted that p53-mediated apoptosis and p53-induced cell cycle checkpoints are the two major mechanisms of p53 protein activity as a tumor
