Cellular localization of GPIIIa by immunofluorescence staining.

Transfected cells were stained simultaneously with AP5, a monoclonal antibody against GPIIIa, and rabbit polyclonal antibodies against mannosidase II (a Golgi marker) or calnexin (an ER marker). (A) Staining with AP5 (green) and anti–mannosidase II (red) shows diffuse GPIIIa in all transfected cells, with no visible aggregation of GPIIIa in the Golgi. The merge, however, does detect small amounts of GPIIIa (yellow color) only in WT and C655S. Original magnification, × 1000. (B) Staining with AP5 (green) and anti-calnexin (red) shows a similar distribution of GPIIIa and ER marker in all types of transformed cells. The substantial AP5 staining in WT and C655S cells probably represents GPIIIa on the cell surface. Original magnification, × 1000.