A gene encoding a 69-kilodalton major surface protein of Giardia intestinalis trophozoites.
A gene encoding a 68.5-kDa trophozoite surface protein (TSP11) of the Australian Giardia intestinalis (syn. G. lamblia) isolate, Ad-1, has been cloned from a genomic expression library screened with an antiserum specific for 3 major surface antigens. Sequence analysis of two overlapping genomic fragments identified a single open reading frame that contained no introns and predicted a cysteine-rich, 667-residue polypeptide with features common to other trophozoite surface proteins. These include the presence of 27 copies of the 4-amino acid Cys-X-X-Cys motif, an N-terminal signal sequence and a highly conserved, hydrophobic C-terminal segment. Transcripts from the tsp11 gene were detected as a single band on Northern blots using total RNA extracted from Ad-1 trophozoites. Primer extension analysis indicated that the mRNA has a 5' untranslated region of only 5 nt, similar to the very short (1-6 nt) leader sequences reported for other Giardia mRNAs. A large portion of the promoter distal segment of tsp11 has homology with tsa417, a gene encoding a 72.5-kDa trophozoite surface antigen of the Afghanistan-derived G. intestinalis isolate, WB [13].
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Department of Microbiology and Immunology, University of Adelaide, Australia.
Khanna
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Manning
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Mayrhofer
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D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D016054:DNA, Protozoan / Q000235:genetics; D017125:Genes, Protozoan; D016829:Giardia lamblia / Q000235:genetics* / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D016053:RNA, Protozoan / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D000954:Antigens, Surface; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan