Transib is a superfamily of

interspersed repeat Interspersed repetitive DNA is found in all eukaryotic genomes. They differ from tandem repeat DNA in that rather than the repeat sequences coming right after one another, they are dispersed throughout the genome and nonadjacent. The sequence that ...

DNA transposon DNA transposons are DNA sequences, sometimes referred to "jumping genes", that can move and integrate to different locations within the genome. They are class II transposable elements (TEs) that move through a DNA intermediate, as opposed to class ...

s. It was named after the

Trans-Siberian Express The Trans-Siberian Railway (TSR; , , ) connects European Russia to the Russian Far East. Spanning a length of over , it is the longest railway line in the world. It runs from the city of Moscow in the west to the city of Vladivostok in the eas ...

. It is similar to EnSpm/CACTA. Transib was first described in 2003, discovered in the ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the " vinegar fly" or "pomace fly". Starting with ...

'' genome. It usually encodes a single protein, DDE transcriptase. An intact element including terminal inverted repeats (TIR) was found in 2008 in the ''

Helicoverpa zea ''Helicoverpa zea, ''commonly known as the corn earworm, is a species (formerly in the genus ''Heliothis'') in the family Noctuidae. The larva of the moth ''Helicoverpa zea'' is a major agricultural pest. Since it is polyphagous (feeds on many ...

'' genome. Divergent clades of this superfamily has since been discovered and dubbed Transib and TransibSU (for sea urchin); Chapaev and Chapaev3 of the CACTA superfamily are sometimes included too. The differences lie in the domain organization of the core transcriptase; TransibSU is also notable for having RAG2-like proteins. Transib is notable as the source of the two

Recombination-activating gene The recombination-activating genes (RAGs) encode parts of a protein complex that plays important roles in the rearrangement and recombination of the genes encoding immunoglobulin and T cell receptor molecules. There are two recombination-activa ...

s. An active transposon with RAG1/2-like genes ("ProtoRAG"; ) has been discovered in ''B. belcheri '' (Chinese lancelet). The TIRs are structurally similar to

Recombination signal sequences Recombination signal sequences are conserved sequences of noncoding DNA that are recognized by the RAG1/RAG2 enzyme complex during V(D)J recombination in immature B cells and T cells. Recombination signal sequences guide the enzyme complex to the ...

(RSS). The heptamer bears the consensus CACWRTG, while the nonamer is more divergent. Lancelet RAG1L/TIR does not cross-recognize animal RAG1/RSS due to differences in the nonamer. '' Psectrotarsia flava'' (a moth) also has such a transposon. It lacks the nonamer, indicating the nonamer's more recent evolution.

References

{{Repeated sequence DNA mobile genetic elements