FIG. 2.

The GFP-LidA fusion protein localizes to early secretory compartments and causes their disruption when overexpressed. (A and B) Immunofluorescence micrographs of COS1 cells expressing GFP-LidA at low (top row) or high (bottom row) levels and stained with antibodies directed against either the ERGIC marker, ERGIC53 (A), or the Golgi marker, GM130 (B). Left, GFPLidA; middle, ERGIC53/GM130; right, merge. Bars, 10 μm. (C and D) Quantification of ERGIC (C) or Golgi (D) disruption in either untransfected COS1 (Untransf.) or transfectants expressing either low levels (Low GFPLidA) or high levels (High GFPLidA) of GFPLidA. The cells were stained with anti-ERGIC53 to assay for ERGIC disruption and with anti-GM130, p115, or TGN46 to assay for disruption of the Golgi, the cis-Golgi, and the trans-Golgi, respectively. The values represent the mean ± standard deviation of three independent experiments.