Intein is an intervening polypeptide which can catalytic self-cleavage from a pre-protein accompanied by the concomitant joining of the two flanking polypeptides (the extein) through a peptide bond.

蛋白质内含肽是一个蛋白质前多肽序列，可催化自身从蛋白质前断裂，两侧蛋白质外显肽连接成成熟蛋白质。