Figure 2

Selective co-precipitation of integrins with CD98. A. HT1080 cells were surface labeled with ¹²⁵I, lysed in 1% Brij 58, then immunoprecipitated with anti-CD98 mAb 6B12. The CD98 immunoprecipitate was then dissociated using 1% Triton X-100 and reprecipitated with mAb to the indicated proteins. Numbers in parentheses above each lane indicate the mean fluorescence intensity of each cell surface antigen as determined by flow cytometry analysis. B. HT1080 cells were labeled overnight with ³⁵S methionine, lysed in 1% Brij 58 then immunoprecipitated with mAb A3-IIF5. Immune complexes were dissociated using 1% Triton X100 and re-precipitated using anti-CD98 mAb 6B12 or anti-CD81 mAb M38. C. Lysates prepared as in Part A were analyzed by immunoprecipitation using mAbs A2-2E10, A3-IIF5, A5-PUJ2, and A6-BB respectively (left 4 lanes). Immunoprecipitation with mAb 6B12 was followed by elution with 1% Triton X100 and reprecipitation with A2-2E10, A3-IIF5, A5-PUJ2, and A6-BB mAb respectively (right 4 lanes). D. Cells transfected with wild type α3 or α3 integrin lacking a cytoplasmic tail (X3C0), were surface-labeled with ¹²⁵I and lysed in 1% Brij 58. Lysates were immunoprecipitated with anti-α3 mAb A3-IIF5 (left 2 lanes) or first immunoprecipitated with mAb 6B12 then subjected to reprecipitation with mAb A3-IIF5 (right 2 lanes). E. Cells transfected with wild type α3 (lane a) or mutant α3 (W220A or Y218A) were cell surface biotinylated and lysed in 1% Brij 58. Lysates were immunoprecipitated with anti-α3 mAb A3-IIF5 (left 3 lanes) or first immunoprecipitated with mAb 4F2 and then subjected to reprecipitation with mAb A3-IIF5 (right 3 lanes).