title: Evidence for a class of very small introns in the gene for hypoxanthine-guanine phosphoribosyltransferase in Schistosoma mansoni.
abstract: The single copy gene for the hypoxanthine-guanine phosphoribosyltransferase (HGPRTase) of the parasitic trematode, Schistosoma mansoni, contains seven introns, the first four of which are only 31, 33, 42, and 32 bases in length. These are the smallest introns ever discovered in a non-viral nuclear gene coding for protein. These very small introns possess the canonical GT...AG splice site sequences but lack the branching sequence, the secondary structure, and the minimum size of approximately 50 bases believed to be required for the splicing of eucaryotic mRNA precursors. Evidently, a somewhat different splicing mechanism for the transcripts of these very small introns is necessary. Their discovery within the genes of helminths raises theoretical considerations for the evolution of introns in eucaryotes.
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco 94143.
authors.forename: S P
authors.initials: SP
authors.lastname: Craig
authors.forename: M G
authors.initials: MG
authors.lastname: Muralidhar
authors.forename: J H
authors.initials: JH
authors.lastname: McKerrow
authors.forename: C C
authors.initials: CC
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D005796:Genes; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D007438:Introns; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D012550:Schistosoma mansoni / Q000201:enzymology / Q000235:genetics*
chemical_list: D007041:Hypoxanthine Phosphoribosyltransferase