Fig. 6. SSeCKS interacts with the GalT cytoplasmic domain in mouse mammary gland cells. (A) Lysates from NMuMG cells expressing GFP only (NMuMG/GFP) or GFP fused to the GalT cytoplasmic and transmembrane domain (NMuMG/TL-GFP) were immunoprecipitated (Ip) with preimmune sera (PI) or with antibodies against SSeCKS (I) and immunoblotted with monoclonal antibodies against GFP. The electrophoretic migration of the expressed GFP and TL-GFP proteins is shown by immunoprecipitation with anti-GFP. Anti-SSeCKS antibodies coprecipitate the TL-GFP fusion protein, whereas GFP does not precipitate with SSeCKS. (B) Lysates from nontransfected (NMuMG) and transfected (NMuMG/TL-GFP) cells were immunoprecipitated with preimmune sera (PI), antibodies against recombinant GalT (I), or antibodies against GFP and immunoblotted with SSeCKS antibodies. Anti-GalT antibodies readily coprecipitate SSeCKS in NMuMG parental cells. Overexpression of the GalT cytoplasmic domain (TL-GFP) leads to a consequent increase in the amount of coprecipitating SSeCKS. The electrophoretic behavior of SSeCKS in NMuMG cell lysates (L) is shown. Molecular mass markers are shown to the left.