Orphan 7-TM Receptors
Orphan 7-TM receptors (orphan GPCRs) are receptors for which there are no defined ligands. Traditionally, receptors are characterized by specific ligands and stimuli; the search for ligands of orphan receptors is akin to reverse-engineering this process, since the receptors have been identified but they are responding to as-yet unidentified endogenous ligands. There are approximately 150 orphan 7-TM receptors, subdivided into three classes: Class A, Class B and Class C. Orphan G-protein coupled receptors are usually identified by number (e.g. GPR35, GPR139) and as they are 'de-orphanized' (by discovery of ligand), they sometimes maintain this prefix (e.g. GPR55). The histamine H4 (GPRv53) and GABAB receptors are further examples of de-orphanized receptors which have recently expanded existing GPCR families.
Screening of putative ligands, reverse pharmacology and the prediction of candidate ligands using structural similarities are three of the methods currently used to isolate ligands for these orphan receptors. Putative ligands for some of the orphan receptors include kynurenic acid (GPR35) and motilin (GPR38). Generation of synthetic ligands for orphan receptors also holds great therapeutic potential: the melanin-concentrating hormone receptor is one such example of a de-orphanized receptor that has developed into a target for obesity, anxiety and depression.There has been great interest in the function of orphan receptors; elucidating the cellular interactions involving them may lead to a greater understanding of existing processes.View all products for Orphan 7-TM Receptors »
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Literature for Orphan 7-TM Receptors
A collection of over 450 products for G protein-coupled receptors, the listing includes research tools for the study of:
- Rhodopsin-like Receptors
- Secretin-like Receptors
- Glutamate Receptors
- Frizzled Receptors
- GPCR Signaling
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