CD9 coimmunoprecipitates with integrin subunit β₁ from CHO A6 but not CHO Δ133-192 cell lysates.

Biotinylated surface proteins from CHO cell lysates were immunoprecipitated with anti-CD9 mAb7 or RAP2, anti-β1 7E2, nonspecific binding mouse IgG, or anti-GPIb AK1, and the immune complexes captured by Protein A/Protein G agarose. (A) Western blots of the immunoprecipitates (IPTs) were probed with NeutrAvidin and developed using SuperSignal. A protein with the apparent molecular weight of CD9 was identified in the mAb7 and 7E2 IPTs from CHO CD9 (A6) cell lysates. (B) mAb7 IPTs from MOCK and CHO A6 cells were dissociated, reimmunoprecipitated using 7E2, and reprobed. A protein corresponding to the apparent molecular weight of β₁ was identified from the CD9 mAb7 IPTs but not from the MOCK mAb7 IPTs. (C) RAP2 IPTs from CHO A6 and CHO Δ133-192 cells were dissociated, reimmunoprecipitated using 7E2, and reprobed. A protein corresponding to the apparent molecular weight of β₁ was identified from the CHO A6 7E2 IPTs of RAP2 eluate but not from the CHO Δ133-192 7E2 IPTs or the AK1 IPTs from CHO A6 or Δ133-192 cells.