Monomeric rhodopsin is sufficient for normal rhodopsin kinase (GRK1) phosphorylation and arrestin-1 binding.

Bayburt TH, Vishnivetskiy SA, McLean MA, Morizumi T, Huang CC, Tesmer JJ, Ernst OP, Sligar SG, Gurevich VV
J Biol Chem. 2011 286 (2): 1420-8

PMID: 20966068 · PMCID: PMC3020750 · DOI:10.1074/jbc.M110.151043

G-protein-coupled receptor (GPCR) oligomerization has been observed in a wide variety of experimental contexts, but the functional significance of this phenomenon at different stages of the life cycle of class A GPCRs remains to be elucidated. Rhodopsin (Rh), a prototypical class A GPCR of visual transduction, is also capable of forming dimers and higher order oligomers. The recent demonstration that Rh monomer is sufficient to activate its cognate G protein, transducin, prompted us to test whether the same monomeric state is sufficient for rhodopsin phosphorylation and arrestin-1 binding. Here we show that monomeric active rhodopsin is phosphorylated by rhodopsin kinase (GRK1) as efficiently as rhodopsin in the native disc membrane. Monomeric phosphorylated light-activated Rh (P-Rh*) in nanodiscs binds arrestin-1 essentially as well as P-Rh* in native disc membranes. We also measured the affinity of arrestin-1 for P-Rh* in nanodiscs using a fluorescence-based assay and found that arrestin-1 interacts with monomeric P-Rh* with low nanomolar affinity and 1:1 stoichiometry, as previously determined in native disc membranes. Thus, similar to transducin activation, rhodopsin phosphorylation by GRK1 and high affinity arrestin-1 binding only requires a rhodopsin monomer.

MeSH Terms (18)

Amino Acid Sequence Animals Arrestins beta-Arrestins Cattle Electrochemistry Fluorescence G-Protein-Coupled Receptor Kinase 1 Leucine Lipids Molecular Sequence Data Mutation Phosphorylation Protein Binding Rhodopsin Signal Transduction Tritium Vision, Ocular

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