BIOCHEMICAL-PROPERTIES OF XENOPUS-LAEVIS P53

The p53 gene has evolutionarily highly conserved boxes from rainbow tr out to man whereas other regions are divergent in different species. I n order to define conserved and species specific properties of p53 we analyzed frog p53. Since the commonly available monoclonal antibodies do not react with Xenopus p53 we expressed a recently cloned Xenopus l aevis cDNA in bacteria and this protein was used to generate polyclona l antibodies. This antibody recognizes p53 from Xenopus laevis oocytes , baculovirus infected insect cells and p53 from an in vitro transcrip tion/translation reaction but not from somatic Xenopus tissue cells. I n contrast to p53 from other species Xenopus p53 is mainly found in th e cytoplasm. Xenopus p53 forms mainly tetramers as p53 from other spec ies. Like p53 from other species Xenopus p53 is tightly associated wit h a protein kinase activity and phosphorylated by this associated enzy me. Xenopus p53 binds strongly to its own RNA without any influence on the translation of p53 mRNA. Thus, Xenopus p53 seems to have some pro perties in common with p53 from other species and some additional spec ies specific features.