Ranhotra Harmit S
Orphan Receptor Laboratory, Department of Biochemistry, St. Edmund's College, Shillong, India.
J Recept Signal Transduct Res. 2011 Feb;31(1):20-5. doi: 10.3109/10799893.2010.538853. Epub 2010 Dec 22.
In classical endocrinology, receptors are molecules that bind a hormone or a ligand to transduce signal within a target cell. Later, however, many intracellular receptors have been discovered in mammals, which have not been shown to bind endogenous ligands and are now are referred as "orphan receptors." The orphan receptors share high degree of structural and functional homology with the classical nuclear receptors (NRs) and are now part of the NR superfamily and therefore referred as orphan nuclear receptors (ONRs). Interestingly, however, ONR members are not evolutionarily or functionally linked and they form a highly diverse group within the NR superfamily. In mammals, ONRs exhibit great functional diversity and majority of them are expressed in a tissue-specific fashion. In the past one decade, functional studies have revealed that they are mediators of multitude of crucial metabolic, developmental, reproductive, and immunological functions in mammals. Emerging studies also indicate the role of ONRs in the onset of several complex human diseases and hence they may be potential candidates for therapeutic drug targeting in the future.
在经典内分泌学中，受体是与激素或配体结合以在靶细胞内转导信号的分子。然而，后来在哺乳动物中发现了许多细胞内受体，它们尚未被证明能结合内源性配体，现在被称为“孤儿受体”。孤儿受体与经典核受体（NRs）具有高度的结构和功能同源性，现在是NR超家族的一部分，因此被称为孤儿核受体（ONRs）。然而，有趣的是，ONR成员在进化或功能上并无关联，它们在NR超家族中形成了一个高度多样化的群体。在哺乳动物中，ONRs表现出极大的功能多样性，其中大多数以组织特异性方式表达。在过去十年中，功能研究表明它们是哺乳动物众多关键代谢、发育、生殖和免疫功能的介质。新出现的研究还表明ONRs在几种复杂人类疾病的发病过程中发挥作用，因此它们可能是未来治疗药物靶向的潜在候选者。
