title: Intron existence predated the divergence of eukaryotes and prokaryotes.
abstract: Nucleotide sequences for the nuclear genes encoding chloroplast (GapA and GapB) and cytosolic (GapC) glyceraldehyde-3-phosphate dehydrogenases (GAPDHs) from Arabidopsis thaliana were determined. Comparison of nucleotide sequences indicates that the divergence of chloroplast and cytosolic GAPDH genes preceded the divergence of prokaryotes and eukaryotes. In addition, some intron-exon junctions are conserved among GapB, GapC, and chicken GAPDH genes. These results provide evidence at the molecular level to support the idea that introns existed before the divergence of prokaryotes and eukaryotes.
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, MA.
authors.forename: M C
authors.initials: MC
authors.lastname: Shih
authors.forename: P
authors.initials: P
authors.lastname: Heinrich
authors.forename: H M
authors.initials: HM
authors.lastname: Goodman
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D005075:Biological Evolution; D002477:Cells; D002645:Chickens / Q000235:genetics; D002736:Chloroplasts / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004926:Escherichia coli / Q000235:genetics; D005057:Eukaryotic Cells; D005091:Exons; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics* / Q000378:metabolism; D007438:Introns; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010944:Plants / Q000235:genetics; D011387:Prokaryotic Cells
chemical_list: D009243:NAD; D009249:NADP; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases