Protein intron is a special kind of inserted polypeptide naturally existing in organisms. It can self-shear at protein level and isolate from the host protein. This process is autocatalytic and does not require the participation of other protein sensitivities.

Insertion region is a non-coding DNA fragment in a gene, which separates adjacent exons. More precisely, introns are sequences that prevent the linear expression of genes. Introns in DNA will be transcribed into precursor RNA, but introns in RNA will be cut off before RNA leaves the nucleus for translation.