STRUCTURAL ORGANIZATION OF THE RAT GENES ENCODING LIVER-TYPE AND HEART-TYPE OF CYTOCHROME-C-OXIDASE SUBUNIT-VIA AND A PSEUDOGENE RELATED TOTHE COXVIA-L CDNA

To study the tissue-specific expression of the heart(H)- and liver(L)- type of rat cytochrome-c oxidase subunit VIa (rCOXVIa), we have screen ed and sequenced the genes for the two isoforms. Both genes contain th ree exons and two introns, spanning 880 bp (rCOXVIa-H) and 3089 bp (rC OXVIa-L), respectively. In both genes, exon I codes for the whole lead er sequence comprising 12 (rCOXVIa-H) or 26 (rCOXVIa-L) amino acids an d for 12 (rCOXVIa-H) or 10 (rCOXV1a-L) amino acids of the correspondin g mature protein, while the remaining amino acids for the mature prote ins are encoded by exons II and III. The 5' region of the genes lack b oth TATA and CAAT boxes, but show a high G+C content in the early 5'-u pstream region. We have identified in upstream regions and in the intr ons of both genes several putative binding sites associated with respi ratory function, muscle gene activation and housekeeping function. In rCOXVIa-H, we identified a CCAC/Myo-D motif, known to be required for muscle-specific expression of the human myoglobin-encoding gene. which is not present in rCOXVIa-L. In addition, we have analyzed a pseudoge ne, showing 84% homology to the COXVIa-L cDNA sequence.