Amino acid sequence of cytochrome c from Tetrahymena pyriformis Phenoset A

Abstract

The cytochrome c of T. pyriformis GL (Phenoset A) had an isoelectric point of 6.5 and a sequence composition of Asp(7) Asn(2) Thr(4) Ser(8) Glu(6) Gln(2) Pro(7) Gly(13) Ala(13) Val(7) Met(2) Ile(5) Leu(6) Tyr(2) Phe(5) Lys(11) His(3) Trp(1) Arg(3) Cys(2) (total 109 residues). The peptides derived from the protein afforded complete overlap, so a complete sequence could be determined without reference to homologous proteins. Alignment with other mitochondrial cytochromes c required 2 internal deletions totalling 3 residues and an N-terminal region 2 residues longer than, and a C-terminal region 1 residue shorter than, the previously known limits. The sequence was the most divergent of the known mitochondrial cytochromes c, suggesting a distant relationship of ciliates to other eukaryotes. Details of the sequence data were deposited as Supplementary Publication SUP 50068 at The British Library Lending Division, Boston Spa, Wetherby; West Yorkshire LS23 7BQ, United Kingdom.