Mutation of the DRY motif reveals different structural requirements for the CC chemokine receptor 5-mediated signaling and receptor endocytosis

Mol Pharmacol. 2005 Jun;67(6):1966-76. doi: 10.1124/mol.104.009779. Epub 2005 Mar 10.


CC chemokine receptor 5 (CCR5) is a G protein-coupled receptor that governs migration of leukocytes and serves as a coreceptor for the R5 tropic strains of human immunodeficiency virus (HIV). CCR5-mediated signaling in response to CC chemokines relies on G protein activation. Desensitization, which rapidly turns off G protein-dependent signaling, involves phosphorylation of CCR5 that promotes interaction of the receptor with beta-arrestins for endocytosis. Whether coupling to G proteins, desensitization, and endocytosis of CCR5 require the same structural determinants remains a matter of investigation. Here, we show that CCR5 displayed agonist-independent coupling to G proteins. This constitutive activity of the receptor was abrogated by TAK779 (N,N-dimethyl-N-[4-[[[2-(4-methylphenyl)-6,7-dihydro-5H-benzocyclohepten-8-yl]carbonyl]amino]benzyl]tetrahydro-2H-pyran-4-aminium chloride), a nonpeptidic CCR5 ligand that inhibits HIV infection and was found to depend on the integrity of the Asp-Arg-Tyr (DRY) motif. Changing Arg-126 by the neutral residue Asn (R126N-CCR5 mutant) abolished CCR5-mediated activation of G proteins, either constitutively or in response to agonists. In contrast, R126N-CCR5 not only retained agonist-promoted phosphorylation and beta-arrestin-dependent endocytosis but also displayed a higher basal phosphorylation than wild-type CCR5. Expression of beta-arrestin in R126N-CCR5-expressing cells resulted in receptor down-regulation, thereby suggesting that R126N-CCR5 spontaneously interacts with beta-arrestins. However, although expression of beta-arrestin favored wild-type CCR5-mediated chemotaxis, it failed to promote migration of cells expressing R126N-CCR5. Overall, these data indicate that structural requirements for CCR5-mediated activation of G proteins, albeit not involved in receptor desensitization and internalization, are needed for beta-arrestin-mediated chemotaxis. These results have implications for how distinct biological responses of CCR5 might rely on a different set of receptor conformations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Arrestins / metabolism
  • Arrestins / pharmacology
  • Cell Line
  • Cricetinae
  • Dose-Response Relationship, Drug
  • Endocytosis / drug effects
  • Endocytosis / physiology*
  • Humans
  • Molecular Structure
  • Mutation*
  • Protein Binding / drug effects
  • Protein Binding / physiology
  • Receptors, CCR5 / chemistry
  • Receptors, CCR5 / genetics*
  • Receptors, CCR5 / physiology*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • beta-Arrestins


  • Arrestins
  • Receptors, CCR5
  • beta-Arrestins