Localization of ligand-induced phosphorylation sites to serine clusters in the C-terminal domain of the Dictyostelium cAMP receptor, cAR1.

摘要: Abstract When Dictyostelium cells are stimulated with cyclic adenosine 3',5'-monophosphate (cAMP), the major surface cAMP receptor expressed in early development, cAR1, undergoes a rapid phosphorylation and parallel decrease electrophoretic mobility which may serve to regulate activity of this G protein-coupled receptor. Biochemical analyses indicate shift is caused by serine residues within C-terminal cytoplasmic domain. The 18 serines domain grouped four clusters, designated 1 4 (in N- order). Two approaches were taken determine distribution sites among clusters. First, proteolytic analysis was performed. Second, mutants lacking various combinations clusters created site-directed mutagenesis their abilities undergo ligand-induced modification determined. Both yielded corroborative results consistent following model: stimulus induces addition approximately two phosphates cluster one 2; basal occurs predominantly 3 lesser extent not phosphorylated. phosphorylation-deficient should be useful for establishing role cAR1 chemotaxis, cell-cell signaling, gene expression.