Figure 4.

Scribble and CD74 copurify from membrane protein isolates and colocalize in stably transfected HEK293s cells. (A) Co-IP/Western blot analysis. Scribble is detected only in the CD74 IP from cells induced with tetracycline to express CD74. (B) Co-IP/MS. Themultiple reaction monitoring (MRM) signal for the reporter peptides is normalized to 100. The values are mean of three replicate LC-MS/MS analyses ± SD. This experimentwas performed twice. First, CD74 expression was induced in the heavy SILAC-labeled cells. Then, the protein was overexpressed in the light SILAC-labeled cells. In both experiments, MaxQuant detected Scribble peptides only in the CD74 IP from tetracycline-induced cells. (C) Colocalization of Scribble and CD74 in HEK293s cells overexprerssing CD74.