Multiprotein complexes involving CMS, CIN85, and CD2BP3 can be recruited to the cytoplasmic domain of human pTα. Total lysates from COS7 cells transfected with the indicated amounts of CD2BP3-Flag (A) or CMS-Flag and CD2BP3-Flag (B) were subjected to pull-down with GST-pTα. Precipitated proteins were analyzed by Western blotting with an anti-Flag mAb. COS7 cells were transiently cotransfected with the indicated amounts of CD2BP3-Flag and CIN85-HA (C) or CD2BP3-Flag, CMS-Flag, and CIN85-HA (D). Total-cell lysates and proteins precipitated with GST-pTα were analyzed by immunoblotting using either an anti-Flag mAb to detect CD2BP3 and CMS (top 2 panels) or an anti-HA mAb to detect CIN85 (bottom 2 panels). *Nonspecific band recognized by the anti-HA antibody. Data are representative of at least 3 independent experiments. Vertical lines have been inserted to indicate a repositioned gel lane.