title: The border residues of the dihydrofolate reductase domain in Escherichia coli beta-galactosidase correspond to the positions of introns 1 and 5 of dihydrofolate reductase of chicken.
abstract: In beta-galactosidase of Escherichia coli residues 820-934 are similar to residues in dihydrofolate reductase of E. coli. Dihydrofolate reductase of E. coli and chicken are also similar and have identical tertiary structures. I used the similarity of the three-dimensional structure of prokaryotic and eukaryotic dihydrofolate reductases to align the chicken dihydrofolate reductase and the similar residues of beta-galactosidase. The positions of introns 1 and 5 of the chicken dihydrofolate reductase gene correspond exactly to the start and the end of the dihydrofolate reductase-like domain in the beta-galactosidase polypeptide chain. This equivalence of intron positions in a eukaryotic gene and domain structure in a prokaryotic protein was interpreted as evidence for a common origin of both genes.
authors.affiliation: Institut für Genetik der Universität zu Köln, FRG.
authors.forename: W
authors.initials: W
authors.lastname: Kuchinke
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics*; D005696:Galactosidases; D007438:Introns; D008969:Molecular Sequence Data; D013762:Tetrahydrofolate Dehydrogenase; D001616:beta-Galactosidase
chemical_list: D013762:Tetrahydrofolate Dehydrogenase; D005696:Galactosidases; D001616:beta-Galactosidase