Role of third intracellular loop of the melanocortin 4 receptor in the regulation of constitutive activity

Do Hun Kim, Seung Woo Shin, Ja Hyun Baik

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The melanocortin 4 receptor (MC4R) has been reported to display constitutive activity, which is probably relevant to the maintenance of a normal energy balance. Among the clinically reported mutants of MC4R in human obesity patients, we investigated the functional characteristics of seven mutants characterized by mutations in the third intracellular (i3) loop of MC4R. Via a CRE (cAMP responsive element)-mediated luciferase reporter gene assay, we show that most of these mutants displayed significantly reduced basal activity with reduced reporter gene activity, whereas the P230L mutant manifested significantly increased basal activity. When the dominant negative Gs mutant was co-expressed, the majority of the mutants, including the P230L mutant, showed reduced basal activity. These results suggest that the i3 loop of MC4R is essential not only for the functional activity but also for the regulation and maintenance of an optimal constitutive activity of MC4R in association with G protein coupling, in the control of energy homeostasis.

Original languageEnglish
Pages (from-to)439-445
Number of pages7
JournalBiochemical and biophysical research communications
Volume365
Issue number3
DOIs
Publication statusPublished - 2008 Jan 18

Keywords

  • Constitutive activity
  • G protein
  • Intracellular loop
  • Melanocortin
  • Melanocortin 4 receptor
  • Mutation
  • Obesity

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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