title: Cytochrome b of protozoan mitochondria: relationships between function and structure.
abstract: 1. The sensitivity of ubiquinol:cytochrome c reductase to its most powerful inhibitors has been characterized in mitochondria from three ciliate and two trypanosome protozoans and compared with that in mitochondria of animals and plants. 2. Mitochondria of ciliates, particularly those of Tetrahymena pyriformis, are resistant to antimycin. 3. Mitochondria of trypanosomes are quite resistant to stigmatellin, as they exhibit a 40-fold higher titer than that in ciliate or animals mitochondria. 4. Both ciliates and trypanosomes are highly resistant to myxothiazol. 5. Correlations have been drawn between the natural resistance of the protozoan mitochondria to antimycin, stigmatellin and myxothiazol and peculiar features in the structure of their apocytochrome b, on the basis of an accurate alignment of the sequences of this protein.
authors.affiliation: Department of Biology, University of Bologna, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Ghelli
authors.forename: M
authors.initials: M
authors.lastname: Crimi
authors.forename: S
authors.initials: S
authors.lastname: Orsini
authors.forename: L
authors.initials: L
authors.lastname: Gradoni
authors.forename: M
authors.initials: M
authors.lastname: Zannotti
authors.forename: G
authors.initials: G
authors.lastname: Lenaz
authors.forename: M
authors.initials: M
authors.lastname: Degli Esposti
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016798:Ciliophora / Q000235:genetics / Q000378:metabolism; D003573:Cytochrome b Group / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014450:Electron Transport Complex III / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D056890:Eukaryota / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010247:Paramecium / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013329:Structure-Activity Relationship
chemical_list: D003573:Cytochrome b Group; D014450:Electron Transport Complex III