Immunoprecipitates of Tyk2 obtained from lysates of Jurkat 76.25 cells after MHC-I or TCR/CD3 ligation. Cells (3 × 10⁷) were preincubated with PBS (lane 1) or saturating amounts of anti-β₂M Ab (lanes 2 through 4) before exposure to avidin for the indicated time (lanes 1 through 4) or exposed to anti-TCR/CD3 Abs (lane 5). Precipitates were immunoblotted with antiphosphotyrosine Ab (upper panel). Blots were stripped and reprobed with anti-Tyk2 Ab (lower panel).