title: Big flies, small repeats: the "Thr-Gly" region of the period gene in Diptera.
abstract: The region of the clock gene period (per) that encodes a repetitive tract of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran species both within and outside the Drosophilidae. All the non-Drosophilidae sequences in this region are short and present a remarkably stable picture compared to the Drosophilidae, in which the region is much larger and extremely variable, both in size and composition. The accelerated evolution in the repetitive region of the Drosophilidae appears to be mainly due to an expansion of two ancestral repeats, one encoding a Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and asparagine or threonine. In some drosophilids the expansion involves a duplication of the pentapeptide sequence, but in Drosophila pseudoobscura both the dipeptide and the pentapeptide repeats are present in larger numbers. In the nondrosophilids, however, the pentapeptide sequence is represented by one copy and the dipeptide by two copies. These observations fulfill some of the predictions of recent theoretical models that have simulated the evolution of repetitive sequences.
authors: Department of Genetics, University of Leicester, United Kingdom.
authors: J
authors: J
authors: Nielsen
authors: A A
authors: AA
authors: Peixoto
authors: A
authors: A
authors: Piccin
authors: R
authors: R
authors: Costa
authors: C P
authors: CP
authors: Kyriacou
authors: D
authors: D
authors: Chalmers
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004175:Diptera / Q000145:classification / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D018428:Drosophilidae / Q000235:genetics*; D017344:Genes, Insect; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D056950:Period Circadian Proteins; D010802:Phylogeny; D012091:Repetitive Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012984:Software
chemical_list: D029721:Drosophila Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins