Cellular and Molecular Biology of Orphan G Protein-Coupled Receptors

Dayoung Oh, Kyungjin Kim, Hyuk Bang Kwon, Jae Young Seong

Research output: Chapter in Book/Report/Conference proceedingChapter

48 Scopus citations


The superfamily of G protein-coupled receptors (GPCRs) is the largest and most diverse group of membrane-spanning proteins. It plays a variety of roles in pathophysiological processes by transmitting extracellular signals to cells via heterotrimeric G proteins. Completion of the human genome project revealed the presence of ∼168 genes encoding established nonsensory GPCRs, as well as 207 genes predicted to encode novel GPCRs for which the natural ligands remained to be identified, the so-called orphan GPCRs. Eighty-six of these orphans have now been paired to novel or previously known molecules, and 121 remain to be deorphaned. A better understanding of the GPCR structures and classification; knowledge of the receptor activation mechanism, either dependent on or independent of an agonist; increased understanding of the control of GPCR-mediated signal transduction; and development of appropriate ligand screening systems may improve the probability of discovering novel ligands for the remaining orphan GPCRs.

Original languageEnglish (US)
Title of host publicationA Survey of Cell Biology
EditorsJeon Kwang
Number of pages56
StatePublished - 2006

Publication series

NameInternational Review of Cytology
ISSN (Print)0074-7696


  • Agonist
  • Antagonist
  • Constitutive activity
  • Deorphaned
  • G protein-coupled receptor
  • Ligand
  • Orphan
  • Screening assay
  • Signaling

ASJC Scopus subject areas

  • Histology
  • Cell Biology


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