Fig. 9.

Translocation of mCD29 to the detergent-insoluble fraction in response to anti-mCD28 mAb requires Tyr-188 but not the other CD28 cytoplasmic tyrosines. Jurkat cells expressing either WT mCD28 or 1 of 10 mCD28 mutants were stimulated with anti-mCD28 mAb without secondary crosslinking. After lysis, CD28 was immunoprecipitated from total or detergent-insoluble fractions and then revealed by immunoblotting; the percentage of translocation was calculated as described in Materials and Methods. Shown are the mean and standard deviations of at least three independent experiments except for Phe-185 and Phe-197 (two independent experiments each).