Fig. 2. Human GRASP55 is a Golgi-localized MPM2 antigen. Jesch S A et al. Mol. Biol. Cell 2001;12:1811-1817 Copyright © 2001 The American Society for Cell Biology Human GRASP55 is a Golgi-localized MPM2 antigen. (A) HeLa cells were transfected with human GRASP55-MYC and processed for double-label immunofluorescence microscopy. The GRASP55-MYC localization pattern as indicated by anti-myc staining is shown. (B) The staining pattern of the Golgi protein giantin in the same cell. Bar, 50 μm. (C) Unsynchronized (I) or mitotic (M) HeLa cells that were mock-transfected (lanes 1 and 2), wild-type (wt) GRASP55-MYC transfected (lanes 3 and 4), or T222A T225A GRASP55-MYC transfected (lanes 5 and 6) were subjected to immunoprecipitation with the anti-myc antibody. The resulting precipitates were analyzed for MPM2 reactivity by immunoblotting. (D) The immunoblot was reprobed with anti-myc antibody to determine GRASP55-MYC recovery. The transfected protein was recovered from both mitotic and interphase cells but only mitotic GRASP55-MYC was MPM2 reactive. As determined by densitometry and after normalization to account for the small difference in protein recovery, the MPM2 reactivity of T222A T225A GRASP55-MYC was 9% that of GRASP55-MYC.