Regulated interactions of the α2A adrenergic receptor with spinophilin, 14-3-3ζ, and arrestin 3

Academic Article

Abstract

  • The present studies demonstrate that no single stretch of sequence in the third intracellular (3i) loop of the α adrenergic receptor (α -AR) can fully account for its previously described interactions with spinophilin (Richman, J. G., Brady, A. E., Wang, Q., Hensel, J. L., Colbran, R. J., and Limbird, L. E. (2001) J. Biol. Chem. 276, 15003-15008), 14-3-3ζ (Prezeau, L., Richman, J. G., Edwards, S. W., and Limbird, L. E. (1999) J. Biol. Chem. 274, 13462-13469), and arrestin 3 (Wu, G., Krupnick, J. G., Benovic, J. L., and Lanier, S. M. (1997) J. Biol. Chem. 272, 17836-17842), suggesting that a three-dimensional surface, rather than a linear sequence, provides the basis for these interactions as proposed for 3i loop tethering of the α -AR to the basolateral surface of Madin-Darby canine kidney cells (Edwards, S. W., and Limbird, L. E. (1999) J. Biol. Chem. 274, 16331-16336). Sequences at the extreme N-terminal and C-terminal ends of the 3i loop are critical for interaction with spinophilin but not for interaction with 14-3-3ζ or arrestin 3, for which the C-terminal half of the loop is more important. Competition binding for S-labeled α -AR 3i loop binding to glutathione S-transferase (GST)-spinophilin amino acids 151-444 revealed a relative affinity of spinophilin ≅ arrestin > 14-3-3ζ for the unphosphorylated α -AR 3i loop. Agonist occupancy of the α -AR increases receptor association with spinophilin, and arrestin 3 appears to compete for this enrichment. However, when the G protein-coupled receptor kinase 2 substrate sequence was deleted from the 3i loop, arrestin 3 could not compete for the agonist-enriched binding of spinophilin to the mutant α -AR. These data are consistent with a model where sequential or competitive interactions among spinophilin, arrestin, and/or 14-3-3ζ play a role in α -AR functions. 2A 2A 2A 2A 2A 2A 2A 2A 35
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    Author List

  • Wang Q; Limbird LE
  • Start Page

  • 50589
  • End Page

  • 50596
  • Volume

  • 277
  • Issue

  • 52