title: No detection of characteristic fungal protein elongation factor EF-3 in Pneumocystis carinii.
abstract: The taxonomic status of Pneumocystis carinii is uncertain, and P. carinii has been categorized both as a fungus and as a protozoan. Recent comparisons of RNA sequence homologies between P. carinii and several genera of fungi and protozoa suggest that P. carinii has closer affinities with the ascomycetes than with the protozoa. The translatory systems of the fungi, however, require three soluble protein factors for peptide chain elongation rather than the two necessary in other eukaryotic systems; to date the additional protein elongation factor (EF-3) appears to be unique to fungi. Western blot analysis of cell-free extracts of P. carinii, derived from rat, was done using a polyclonal antibody raised in rabbits to Saccharomyces cerevisiae EF-3. Anti-EF-3 cross-reacting material was detected only in lysates of Candida albicans and S. cerevisiae included as fungal controls; no cross reaction was detected in lysates of P. carinii, P. carinii-infected rat lung, or a protozoan control (Trichomonas vaginalis).
authors.affiliation: Chemotherapy Department, Glaxo Group Research, Greenford, United Kingdom.
authors.forename: H C
authors.initials: HC
authors.lastname: Jackson
authors.forename: D
authors.initials: D
authors.lastname: Colthurst
authors.forename: V
authors.initials: V
authors.lastname: Hancock
authors.forename: M S
authors.initials: MS
authors.lastname: Marriott
authors.forename: M F
authors.initials: MF
authors.lastname: Tuite
mesh_terms: D000818:Animals; D015153:Blotting, Western; D003429:Cross Reactions; D005656:Fungal Proteins / Q000032:analysis*; D010445:Peptide Elongation Factors / Q000032:analysis*; D011010:Pneumocystis / Q000032:analysis / Q000145:classification* / Q000302:isolation & purification; D011020:Pneumonia, Pneumocystis / Q000382:microbiology; D051381:Rats; D011919:Rats, Inbred Strains; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; D010445:Peptide Elongation Factors; D029701:Saccharomyces cerevisiae Proteins; C111584:YEF3 protein, S cerevisiae