Originally identified as multicopy suppressor of a lethal growth arrest caused by expression of a tumour mutant cDNA of p53 in fission yeast the tms1 gene product was found to form stable complexes with p53 in yeast. By using purified recombinant proteins multimeric complexes of tms1 and p53 could be demonstrated and recently the p53 binding site on the tms1 protein was established to the sequence YYITTEDFCT (aa 116-125) in the vicinity of a well conserved cell division motif. Here we report the precise mapping of the tms1 binding site on the p53 protein to the sequence LQIRGRERFE (aa 330-339) which defines a new functional domain on the p53 protein.