Figure 7.

Subcellular localization of SARS coronavirus M protein and its mutants. HeLa cells were transfected with expression plasmids for V5-tagged SARS coronavirus M protein and its TM1′, TM2′ and TM3′ mutants. Cells were then stained for V5 and a marker protein. Nuclear morphology (blue) was visualized with DAPI. Specific fluorescent signals from V5 and the marker were then merged. Transfected cells in the merged panels are highlighted by arrows. Colocalization appeared yellow. GM130 and calnexin serve as markers for the Golgi complex and the ER, respectively. All panels shown are representative of the results of triplicate experiments. Whereas significant colocalization of M and TM1′ with GM130 was seen in 83% and 87% of 100 transfected cells, TM2′ and TM3′ colocalized with calnexin significantly in 66% and 73% of 100 transfected cells. Bar=20 µm. DAPI, 4′,6-diamidino-2-phenylindole; ER, endoplasmic reticulum; IFN, interferon; SARS, severe acute respiratory syndrome.