Skip to main content
eScholarship
Open Access Publications from the University of California

The interaction of a constitutively active arrestin with the arrestin-insensitive 5-HT2A receptor induces agonist-independent internalization

  • Author(s): Gray, JA
  • Bhatnagar, A
  • Gurevich, VV
  • Roth, BL
  • et al.
Abstract

5-HT2Aserotonin receptors are unusual among G-protein coupled receptors in that they can be internalized and desensitized, in some cell types, in an arrestin-independent manner. The molecular basis of the arrestin-insensitivity of 5-HT2Areceptors is unknown but is probably caused, in part, by the apparent lack of agonist-induced 5-HT2Areceptor phosphorylation. Because the arrestin-insensitivity of 5-HT2Areceptors is cell-type selective, we used a "constitutively active" arrestin mutant that can interact with agonist-activated but nonphosphorylated receptors. We show here that this "constitutively active" arrestin mutant (Arr2-R169E) can force 5-HT2Areceptors to be regulated by arrestins. Cotransfection of 5-HT2Areceptors with Arr2-R169E induced agonist-independent 5-HT2Areceptor internalization, and a constitutive translocation of the Arr2-R169E mutant to the plasma membrane, whereas wild-type Arrestin-2 had no effect. Additionally, Arr2-R169E, unlike wild-type arrestin-2, induced a significant decrease in efficacy of agonist-induced phosphoinositide hydrolysis with an unexpected increase in agonist potency. Radioligand binding assays demonstrated that the fraction of receptors in the high-affinity agonist binding-state increased with expression of Arr2-R169E, indicating that Arr2-R169E stabilizes the agonist-high affinity state of the 5-HT2Areceptor (R*). Intriguingly, the agonist-independent interaction of Arr2-R169E with 5-HT2Areceptors was inhibited by inverse agonist treatment and is thus probably caused by the high level of 5-HT2Areceptor constitutive activity. This is the first demonstration that a constitutively active arrestin mutant can both induce agonist-independent internalization and stabilize the agonist-high affinity state of an arrestin-insensitive G protein coupled receptor.

Many UC-authored scholarly publications are freely available on this site because of the UC Academic Senate's Open Access Policy. Let us know how this access is important for you.

Main Content
Current View