分子伴侣（英文：Chaperone，又见称为：molecular chaperone,中文又可译为侣伴蛋白。英文单词原意是指姆，即负责监管、教育年轻未婚少女的行为的老年妇女。）是一类协助细胞内分子组装和协助蛋白质折叠的蛋白质。注意，分子伴侣与伴侣素（英文：Chaperonin）的区别。后者只是分子伴侣中的一种，前者还包括热休克蛋白Hsp60和Hsp10两个家族。另外，使用ATP协助蛋白质折叠只是一部分分子伴侣的功能，分子伴侣如Asf1者，能在细胞分裂过程中提升DNA解螺旋酶的活性并且将母链的组蛋白传递到子链。

Chaperonins are proteins that provide favourable conditions for the correct folding of other proteins, thus preventing aggregation. Newly made proteins usually must fold from a linear chain of amino acids into a three-dimensional form. Chaperonins belong to a large class of molecules that assist protein folding, called molecular chaperones. The energy to fold proteins is supplied by adenosine triphosphate (ATP).