FIG. 4.

Intracellular localization of pp28. Cos7 cells were transfected with an expression plasmid bearing the gene encoding pp28 and then fixed 48 h later as described in Materials and Methods. The cells were reacted with either pp28-specific MAb or polyclonal rabbit anti-pp28 antibodies and the corresponding cell marker. We used the following markers for compartments in the secretory system: (i) calreticulin for the ER, (ii) ERGIC 53 for the ERGIC, (iii) GM130 for the Golgi apparatus, (iv) WGA for the TGN, and (v) LAMP-1 for lysosomes. Colocalization was considered significant when the merged signal revealed a yellow color associated with a distinct cellular site or structure and not in a more generalized location within the cell.