Open Close
General Information
D. melanogaster
Feature type
FlyBase ID
Sequences and Components
Terminal repeat (bp)
Component genes
Sequence Accessions
GenBank Nucleotide - A collection of sequences from several sources, including GenBank, RefSeq, TPA, and PDB.
Sequence Ontology (SO)
Insertions and Copy Number
Copy number and comments


2 in euchromatin of Release 3 genome annotation, of which 1 is full length.

TE copies retrieved from release 5.1 of the D. melanogaster genome.:11

Target Site Duplication

The single full length 1731 element does not have a frameshift between the 1731\gag and 1731\RTase genes, so is expected to express a 1731\gag-1731\RTase fusion protein.

Two classes of 1731 element are present in the genome. The first class uses conventional translational frameshifting to ensure expression of the 1731\RTase open reading frame. Most of the genomic copies are related to the second class where the frameshift is prevented as a result of a substitution of a rare codon recognising a rare tRNA by a codon preferred by the host genome and the 1731\RTase ORF is restored by a downstream single nucleotide deletion.

Expression of 1731 is regulated not only at the transcriptional level but also at the translational level, this regulation is different in the two sexes.

Used in an investigation to address the relationship between retrotransposons and retroviruses and the coadaptation of these retroelements to their host genomes. Results indicate retrotransposons are heterogeneous in contrast to retroviruses, suggesting different modes of evolution by slippage-like mechanisms.

UVB-irradiation activation of 1731-LTR requires a short sequence of the U3 region, the sequence is active in human or Schneider cell line. Sequence is similar to the binding sequence of members of the nuclear factor κB (NF-κB)/rel family.

In vitro transcription of the 1731 element promoter is repressed by NssBF element binding protein(s).

Overexpression of Ssb-c31a in transfected cells represses the 1731 element promoter.

The distribution of a number of transposable elements has been studied in 10 Harwich mutation accumulation lines.

Estimating the genomic numbers of transposable elements demonstrates many families of element are over-represented in heterochromatin.

The spatial and temporal expression patterns of fifteen families of retrotransposons are analysed during embryogenesis and are found to be conserved. Results suggest that all families carry cis-acting elements that control their spatial and temporal expression patterns.

The 1731 promoter is active in Pleurodeles waltl oocytes suggesting in the case of horizontal transfer 1731 can be expressed in vertebrate organisms.

Element copy numbers on inversion and standard chromosomes has been determined. The copy number is significantly higher within low frequency inversions than within the corresponding standard chromosome regions.

The behaviour of the LTR is analysed after transfer to human monocytes.

The distribution of 1731 retrotransposon-hybridising sequences reveals the sequences are widespread within both the Sophophora and Drosophila subgenera. The 1731 retrotransposon family appears to have a long evolutionary history in the Drosophilidae genome.

Top2 is involved in different functions of the 1731 LTR.

Stability of 11 transposable element families compared by Southern blotting among individuals of lines that had been subjected to 30 generations of sister sib matings. 412, roo, blood, 297, 1731 and G-element all appear stable, whereas copia, hobo, I-element, gypsy and jockey elements show instability.

The genomic distribution of transposable elements in somatic tissues and during development is homogeneous.

A retroviral-like transposable element. The first 1731 element was identified because its transcription in tissue-culture cells is reduced in the presence of 20-hydroxyecdysone (FBrf0045155). In cell lines the transcription of 1731 is down-regulated by ecdysteroids (FBrf0053421; FBrf0054856).

Other Information
External Crossreferences and Linkouts ( 7 )
GenBank Nucleotide - A collection of sequences from several sources, including GenBank, RefSeq, TPA, and PDB.
DroID - A comprehensive database of gene and protein interactions.
Synonyms and Secondary IDs (6)
References (134)