Agonist-induced Loss of Ligand Binding Is Correlated with Phosphorylation of cAR1, a G Protein-coupled Chemoattractant Receptor from Dictyostelium

摘要: Abstract The parallel agonist-induced phosphorylation, alteration in electrophoretic mobility, and loss of ligand binding a guanine nucleotide-binding regulatory protein (G protein)-coupled chemoattractant receptor from Dictyostelium (cAR1) depend upon cluster five C-terminal domain serine residues (Caterina, M. J., Hereld, D., Devreotes, P. N. (1995) J. Biol. Chem. 270, 4418-4423). Analysis mutants lacking combinations these serines revealed that either Seror Seris required; both are defective all responses. Interestingly, several mutants, including those substituted at only Ser, or non-serine positions within the third cytoplasmic loop, displayed an unstable mobility shift; was rapidly reversed cAMP removal. These also exhibited subnormal extents binding, which is assessed after removal ligand. For wild-type receptor, we found stability phosphorylation depends concentration duration agonist pretreatment. This suggests that, following cAR1 undergoes further transition (EC≈ 140 n M, t≈ 4 min) to relatively phosphatase-resistant state. We used this insight show under conditions tested, extent correlated with fraction altered form. discuss possible relationships between binding.