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.

蛋质内含是一个蛋质前体中的多序列，可以催化自身从蛋质前体中，两侧的蛋质外显连接成成熟的蛋质。