Turkey cytochrome c oxidase contains subunit VIa of the liver type associated with low efficiency of energy transduction.
Eur J Biochem, 2000/4;267(7):2098-104.
Hüttemann M[1], Arnold S, Lee I, Mühlenbein N, Linder D, Lottspeich F, Kadenbach B
Affiliations
PMID: 10727950
Abstract
Cytochrome c oxidase was isolated from turkey liver, heart and breast skeletal muscle and separated by SDS/PAGE. The N-terminal amino-acid sequence of subunit VIa from all tissues and internal sequences from the skeletal muscle enzyme show homology to the mammalian liver-type subunit VIaL, which was verified by isolation and sequencing of the cDNA of turkey subunit VIa. No cDNA corresponding to subunit VIaH (mammalian heart-type) could be found by RACE-PCR with mRNA from all turkey tissues. Measurement of proton translocation with the reconstituted enzymes from turkey liver and heart revealed H+/e- ratios below 0.5 that were independent of the intraliposomal ATP/ADP ratio, as previously found with the bovine liver enzyme. Under identical conditions, the bovine heart enzyme revealed H+/e- ratios of 0.85 at low and 0.48 at high intraliposomal ATP/ADP ratios. The results suggest that in birds the lower H+/e-ratio of cytochrome c oxidase participates in elevated resting metabolic rate and thermogenesis.
MeSH terms
Adenosine Diphosphate; Adenosine Triphosphate; Amino Acid Sequence; Animals; Base Sequence; DNA Primers; DNA, Complementary; Electron Transport Complex IV; Energy Metabolism; Liver; Molecular Sequence Data; Muscle, Skeletal; Myocardium; Sequence Homology, Amino Acid; Turkeys
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