ABSTRACT
We determined the complete nucleotide sequence of the gypsy element present at the forked locus of Drosophila melanogaster in the f1 allele. The gypsy element shares more homology with vertebrate retroviruses than with the copia element of D. melanogaster or the Ty element of Saccharomyces cerevisiae, both in overall organization and at the DNA sequence level. This transposable element is 7,469 base pairs long and encodes three putative protein products. The long terminal repeats are 482 nucleotides long and contain transcription initiation and termination signals; sequences homologous to the polypurine tract and tRNA primer binding site of retroviruses are located adjacent to the long terminal repeats. The central region of the element contains three different open reading frames. The second one encodes a putative protein which shows extensive amino acid homology to retroviral proteins, including gag-specific protease, reverse transcriptase, and DNA endonuclease.
Subject(s)
DNA Transposable Elements , Drosophila melanogaster/genetics , Genes, Viral , Genes , Retroviridae/genetics , Viral Proteins/genetics , Amino Acid Sequence , Animals , Base Sequence , DNA Restriction Enzymes , Plasmids , Sequence Homology, Nucleic AcidABSTRACT
We cloned a Drosophila melanogaster ras gene (Dmras64B) on the basis of its homology to the ras oncogen from Harvey murine sarcoma virus. This gene mapped at chromosomal position 64B on the left arm of the third chromosome. Sequencing of Dmras64B revealed extensive amino acid homology with the proteins encoded by the human and Saccharomyces cerevisiae ras genes. The coding region of the Drosophila gene is interrupted by two introns located in different positions with respect to its human counterpart. Dmras64B encodes three different RNAs (1.6, 2.1, and 2.6 kilobases long) that are constantly expressed throughout the development of the fly.
