Co-IP of tagged GP Ibα, GP Ibβ, and GP IX in the GP Ib-IX complex from CHO cells. The HA and myc tags were, respectively, appended to the C-terminus of (A) GP Ibβ, (B) GP Ibα, or (C) GP IX. The CHO cells were transiently transfected with indicated subunits, and cell lysates were immunoprecipitated with antibodies, resolved in a 4% to 12% Bis-Tris SDS gel under nonreducing (N.R.) or reducing (R.) conditions, and blotted with HRP-conjugated anti-HA antibody. In the lanes marked by —, the lysates were loaded directly onto the SDS gel.