IL-4– and IL-7–induced tyrosine phosphorylation of Jak3 kinase is attenuated in the cells expressing the transfected mutant γc chain obtained from the X-SCID patient. (A) ED-7R.cl1 cells, ED-γc-7R.cl1 cells, ED-γc-7R.cl3 cells, ED-AV-7R.cl2 cells, and ED-AV-7R.cl8 cells were stimulated with 10 nmol/L of IL-2, IL-4, IL-7, and IL-15 for 15 minutes. The cell lysates were immunoprecipitated with anti-Jak3 polyclonal antibodies, separated by SDS-PAGE, and transferred to membranes. Phosphotyrosine was detected by antiphosphotyrosine MoAb, 4G10. The filters were reprobed with the anti-Jak3 polyclonal antibodies to determine the amount of Jak3 in each lane. (B) ED-γc-7R.cl1 cells and ED-AV-7R.cl2 cells were stimulated with various concentration of IL-2, IL-7, and IL-15 for 15 minutes. The cell lysates were immunoprecipitated with anti-Jak3 polyclonal antibodies, and phosphotyrosine-containing proteins were detected by immunoblotting with 4G10. The position of Jak3 is shown by the arrow. Molecular sizes are indicated on the left (in kD).