Agonist-induced endocytosis and receptor phosphorylation mediate resensitization of dopamine D(2) receptors

Mol Endocrinol. 2010 Mar;24(3):574-86. doi: 10.1210/me.2009-0369. Epub 2010 Feb 16.


The regulatory mechanisms and functional roles of agonist-induced internalization of G protein-coupled receptors (GPCRs) were analyzed using mutant dopamine D(2) receptors (D(2)Rs) in which all possible GPCR kinase (GRK) phosphorylation sites were mutated or the affinity for beta-arrestins was altered. Agonist-induced internalization of D(2)Rs involved a phosphorylation-dependent component, which was mediated by serine/threonine (S/T) residues in the second loop and T225 in the third loop, and a phosphorylation-independent component. GRK2-mediated enhancement of the internalization and inhibition of D(2)R signaling did not involve receptor phosphorylation, and only the former required the enzymatic activity of GRK2. The phosphorylation-deficient mutant (D(2)R-intracellular loop 2/3) recycled more slowly and showed more agonist-induced desensitization than did the wild-type D(2)R, suggesting that receptor phosphorylation mediates the recycling of the internalized receptors and enhances receptor resensitization. Blockade of the agonist-induced internalization of D(2)R-intracellular loop 2/3 provoked desensitization as in wild-type D(2)R, suggesting that certain cellular processes other than receptor dephosphorylation occurring within the endocytic vesicle are responsible for the resensitization of D(2)R. When dissociation between D(2)R and beta-arrestin was inhibited or when the expression of cellular beta-arrestins was decreased, agonist-induced desensitization of D(2)R did not occur, suggesting that dissociation from beta-arrestin is the main cellular process required for resensitization of D(2)R and is achieved through agonist-induced internalization. These results indicate that, in the regulation of some GPCRs, phosphorylation-independent association with beta-arrestin plays a major role in agonist-induced desensitization.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arrestins / genetics
  • Arrestins / metabolism
  • Cell Line
  • Cyclic AMP / metabolism
  • Dopamine / metabolism
  • Endocytosis / drug effects*
  • Endocytosis / genetics
  • Humans
  • Immunoprecipitation
  • Isoproterenol / pharmacology
  • Models, Biological
  • Molecular Sequence Data
  • Mutation
  • Phosphorylation / drug effects
  • RNA, Small Interfering
  • Receptors, Dopamine D2 / agonists*
  • Receptors, Dopamine D2 / chemistry
  • Receptors, Dopamine D2 / genetics
  • Receptors, Dopamine D2 / metabolism*
  • beta-Arrestins


  • Arrestins
  • RNA, Small Interfering
  • Receptors, Dopamine D2
  • beta-Arrestins
  • Cyclic AMP
  • Isoproterenol
  • Dopamine