Subunit IV of human cytochrome c oxidase, polymorphism and a putative isoform.
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Van Kuilenburg AB, Van Beeumen JJ, Demol H, Van den Bogert C, Schouten I, Muijsers AO
Subunit IV of human cytochrome c oxidase, polymorphism and a putative isoform.
Biochim Biophys Acta. 1992 Feb 26;1119(2):218-24.
- PubMed ID
- 1311608 [ View in PubMed]
- Abstract
As part of our study of isoenzyme forms of human cytochrome c oxidase, we purified subunit IV from human heart and skeletal muscle with reversed-phase HPLC and determined the N-terminal amino acid sequences and the electrophoretic mobility. The N-terminus of human heart subunit IV proved to be ragged with 30% of the protein lacking the first three residues. Also a Tyr/Phe polymorphism was observed at residue 16. No differences in N-terminal sequence and electrophoretic mobility were observed between subunit IV of cytochrome c oxidase from human heart and skeletal muscle. Therefore, our results suggest that identical subunits IV are present in cytochrome c oxidase from human heart and skeletal muscle. A putative isoform of subunit IV with a blocked N-terminus was purified from human heart cytochrome c oxidase, which proved to have a different retention time on a reversed-phase column and also a slightly higher electrophoretic mobility on an SDS-polyacrylamide gel compared to the native subunit IV. We could not demonstrate the existence of isoforms of subunit IV in human skeletal muscle.