A SPLICE DONOR SITE MUTATION RESULTS IN THE INSERTION OF 5 EXTRA AMINO-ACIDS INTO P53 FROM SEWA MOUSE SARCOMA-CELLS

The status of the p53 gene in SEWA-AS12-ADH (S-ADH) cells, a subline o f the mouse sarcoma cell line SEWA, was examined. Immunoprecipitation with wild-type (wt) or mutant P53-specific monoclonal antibodies (mAb) showed that both wt and mutant P53 were produced. Sequence analysis o f the p53 cDNA and genomic DNA revealed a single nucleotide (nt) subst itution at a splice donor site at the beginning of intron 7. As a resu lt of this mutation, an alternative splice site 15 nt further 3' in in tron 7 is used. The P53 protein translated from this aberrantly splice d mRNA carries an Arg(258)-->Ser substitution, followed by an insertio n of 5 extra amino acids. This is the first example of a splice-site m utation in the mouse p53 gene.