Retroposon

Retroposons are repetitive DNA fragments which are inserted into chromosomes after they had been reverse transcribed from any RNA molecule.

Non-long terminal repeat (LTR) retrotransposons such as the human LINE1 elements are sometimes falsely referred to as retroposons.

Retrotransposons also feature LTRs and retroviruses, in addition, are packaged as viral particles (virions).

A classical event is the retroposition of a spliced pre-mRNA molecule of the c-Src gene into the proviral ancestor of the Rous sarcoma virus (RSV).

The retroposed c-src pre-mRNA still contained a single intron and within RSV is now referred to as v-Src gene.