CYTOCHROME-C-OXIDASE SUBUNIT-I FROM THE COCKROACH BLATTELLA-GERMANICA- CLONING, DEVELOPMENTAL PATTERN AND TISSUE EXPRESSION

The nucleotide sequence of a cDNA corresponding to the transcription p roduct of the mitochondrial structural gene cytochrome c oxidase subun it I was determined. A polypeptide of 508 residues was deduced from th e reading frame established by the nucleotide sequence. TGA codes tryp tophan, as in most other mitochondrial systems. From the comparison of the amino acid sequence of the putative Blattella germanica cytochrom e c oxidase with those of Drosophila, we conclude that ATA and AGA cod ons specify methionine and serine respectively, instead of isoleucine and arginine. The sequence proposed for cytochrome c oxidase subunit I of B. germanica is largely homologous to that of other species. From the alignment of cytochrome c oxidase subunit I protein sequences we h ave found that 125 residues (positional identity of 22.3%) have remain ed invariant in this enzyme for more than one billion years of diverge nce. There is a developmental pattern of gene expression affecting the embryo stages. Northern blot analysis of RNA samples from different a dult female tissues shows high cytochrome c oxidase subunit I mRNA lev els in gut and fat body, and lower levels in ovary and colleterial gla nds.