Phosphorylation of the intracellular domain of FcαRI.

The intracellular domain of CD89 is constitutively phosphorylated in nonprimed cells. This phosphorylation is critically controlled by S263. GST-tagged intracellular domains of CD89 are used for an in vitro kinase assay with eosinophil and Ba/F3 lysates. Hereafter, constructs are “fished” with glutathione-coated beads and visualized by autoradiography (upper panels) and protein staining for checking equal loading (lower panels). The experiment shown is representative of 3 additional experiments.