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体中的多肽序列，可以催化自身从蛋白质前体中断裂，使两侧的蛋白质外显肽连接成成熟的蛋白质。