Isolation of human fibroblast catalase cDNA clones. Sequence of clones derived from spliced and unspliced mRNA.

We report the isolation and sequence of partial cDNA clones coding for human catalase. These clones were recovered from a human fibroblast cDNA library by screening with mixtures of oligonucleotide probes deduced from the amino acid sequence of human erythrocyte catalase. A comparison of their nucleotide sequence with the known protein sequence and mapping of homologous DNA sequences to the short arm of chromosome 11 in somatic cell hybrids confirmed that they coded for catalase. One of these clones contained a 462-base insertion interrupting the coding sequence with stop codons in all three reading frames. The 5' and 3' ends of the insertion correspond to the donor and acceptor consensus sequences of introns. Inspection of clones lacking the insertion confirm the location of the splice sites. We suggest this clone corresponds to the product of reverse transcription of an unspliced mRNA species. The catalase gene is the closest genetic marker mapped to Wilms tumor, one of the most prevalent of childhood cancers. Catalase cDNA probes will be useful to the examination of mitotic recombination in the etiology of this disease and may provide a useful starting point to the search for the putative Wilms tumor gene.