Figure 4.

Immunoprecipitation of α4 mutants. Lysates from surface ¹²⁵I-labeled cells expressing wild-type (wt) or mutant α4 were immunoprecipitated with mAb B5G10; 0.3% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) was used as a detergent. For R3c, polyclonal anti-α4 rabbit serum and 1% Triton X-100/0.5% Tween 20 were used instead of B5G10 and CHAPS. Immunoprecipitated materials were analyzed by SDS/PAGE (7% gel) under nonreducing conditions. A faint protein band just above α4 might be a 180-kDa form of α4 (22). Control mouse IgG did not precipitate anything from any of the cell lines used (data not shown).