title: Occurrence of a copia-like transposable element in one of the introns of the potato starch phosphorylase gene.
abstract: The gene coding for starch phosphorylase (EC 2.4.1.1) was isolated from a potato genomic library constructed in lambda EMBL3. It is an unusually long plant gene (16.4 kb) which encodes a preprotein of 966 amino acids. The phosphorylase coding sequence is interrupted by 14 introns whose positions do not match those of the introns in the human glycogen phosphorylase gene. A 78 amino acid central peptide unique to plant plastidial phosphorylases is hypothesized to have arisen through the mis-splicing of an intron-exon junction site in an ancestral gene. The fifth intron of the phosphorylase is very large (approximately 7 kb) and contains a copia-like transposable element inserted in the opposite orientation to that of the phosphorylase gene. This element has been named Tst1; it is bordered on the 5' and 3' sides by long terminal repeats of 285 and 283 bp respectively, which define an internal domain of 4492 bp. Tst1 contains 4 open reading frames (ORFs) that encode protein domains for a reverse transcriptase, an integrase, an RNA-binding site and a protease. Transcription of the phosphorylase gene appears to proceed unimpaired through the copia element.
authors.affiliation: Département de Biochimie, Université de Montréal, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Camirand
authors.forename: B
authors.initials: B
authors.lastname: St-Pierre
authors.forename: C
authors.initials: C
authors.lastname: Marineau
authors.forename: N
authors.initials: N
authors.lastname: Brisson
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002736:Chloroplasts / Q000201:enzymology; D004254:DNA Nucleotidyltransferases / Q000235:genetics; D004251:DNA Transposable Elements; D010450:Endopeptidases / Q000235:genetics; D017343:Genes, Plant; D019426:Integrases; D007438:Introns; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D006005:Phosphorylases / Q000235:genetics*; D012313:RNA / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000235:genetics; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D004251:DNA Transposable Elements; D012313:RNA; D006005:Phosphorylases; D004254:DNA Nucleotidyltransferases; D019426:Integrases; D012194:RNA-Directed DNA Polymerase; D010450:Endopeptidases