Fig. 8. Localization and association of IQGAP1 with sites of protein synthesis and exocytosis. (A) Confocal slice (0.16 µm) showing the co-localization of IQGAP1 (red) with the ER marker calnexin (green) in HeLa cells. Arrows indicate localization spots. (B) Co-localization of IQGAP1 (red) with the ER resident marker IP₃R3 (green) in NIH3T3 cells. (C) Co-localization of IQGAP1 (red) with the t-SNARE syntaxin 1A (green) in HeLa cells. No post-image-acquisition processing was performed. Arrows indicate plasma membrane leading edge or ruffles. (D) Top: co-immunoprecipitation of IQGAP1 with the ER-translocon subunit Sec61β. Monoclonal antibodies for Sec61β or IQGAP1 were used conversely for IP. The immune complexes were resolved on a 15% SDS-PAGE and conversely blotted with anti-IQGAP1 or -Sec61β antibodies. Bottom: co-immunoprecipitation of IQGAP1 and syntaxin 1A (Synt1A). Anti-Synt1A or -IQGAP1 antibodies were used for IP, and the immune complexes resolved on a 10% SDS-PAGE and conversely blotted with the indicated antibodies.