Editing Protein splicing (section)

==== Full and mini inteins ====
Inteins can contain a [[Homing endonuclease| homing endonuclease gene]] (HEG) domain in addition to the splicing domains. This domain is responsible for the spread of the intein by cleaving DNA at an intein-free [[allele]] on the [[homologous chromosome]], triggering the [[DNA repair#Double-strand breaks|DNA double-stranded break repair]] (DSBR) system, which then repairs the break, thus copying the intein-coding DNA into a previously intein-free site.<ref name="pmid33339089"/> The HEG domain is not necessary for intein splicing, and so it can be lost, forming a ''minimal'', or ''mini'', ''intein''. Several studies have demonstrated the modular nature of inteins by adding or removing HEG domains and determining the activity of the new construct.{{Citation needed| date=November 2011}}