Nucleotide sequence of cDNA encoding subunit VIIa of rat liver cytochrome c oxidase.

Mammalian cytochrome c oxidase (COX) is composed of three catalytic, on mitochondrial DNA encoded subunits, and ten nuclear encoded subunits, which have been ascribed a regulatory function (1). At least three nuclear encoded subunits occur in tissue-specific isoforms (Via, Vila and VIE). The liverand hearttype cDNA has been described for rat subunit Via (2) and bovine subunit Vm (3). The liver-type cDNA for COX subunit Vila was described from bovine (4) and human (5). The bovine cDNA gene probe was used to isolate an incomplete cDNA for subunit VHa (liver-type) from a rat heart cDNA library in lambda gtl 1 (Genofit). This cDNA was used as a probe to identify the fulllength cDNA from a rat total fetal cDNA library in lambda gtl 1 (see below). The deduced amino acid sequence of the mature polypeptide is 83 % identical to the bovine liver COX Vila (4) and 73% identical to the human liver COX VHa (5), but only 63% identical to bovine heart COX Vila (R.S.Seelan and L.I.Grossman, unpublished results). A 23 amino acid sequence (underlined) precedes the mature polypeptide.