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.

蛋白质内含是一个蛋白质前多序，催化自身从蛋白质前断裂，使两侧蛋白质外显连接成成熟蛋白质。