SiRNA-immune Yip1A transgene to rescue the whorled ER phenotype in knockdown cells [10], we carried out a systematic mutational analysis of nearly all residues in the protein; our goal being to determine those residues most important for its ER structural maintenance role.C-terminus. The HA-Yip1A D1-83 and D1-118 constructs were created using the PCR-based loop-out technique (Madrasin Stratagene). All additional HA-Yip1A mutant constructs were created using QuikChange site directed mutagenesis PCR (Stratagene). siRNAs directed against Yif1A were created using a siRNA construction kit (Ambion) and previously published target sequences [13]. The control siRNA used in this study targets bovine p115 and does not affect p115 in HeLa cells [29].Antibodies, immunofluorescence and immunoblottingAntibodies used include mouse monoclonal antibody (mAb) against the HA-epitope (Sigma-Aldrich, St. Louis, MO); a rabbit polyclonal antibody (pAb) against Calnexin, a pAb against tubulin and a mAb against protein disulfide isomerase (PDI) (both Abcam, Cambridge, MA); the 9E10 mAb against the myc epitope [30]; a pAb against GPP130 (kindly provided by Dr. A. Linstedt, Carnegie Mellon University, Pittsburgh, PA). Fluorophore-conjugated secondary antibodies were from Zymed Laboratories (South San Francisco, CA)/Invitrogen (Carlsbad, CA). HeLa cells were typically analyzed 72 h post-transfection. Immunofluorescence procedures were as described previously [10]. Immunoblotting using a mouse mAb against the myc-epitope and a rabbit pAb against tubulin (Abcam), was performed on cells co-transfected with Yif1A siRNA and myc-Yif1A harvested from 60-mm dishes as described previously [31].Materials and Methods Cell culture and transfectionsHeLa cells stably expressing a GalNacT2-green fluorescent protein (GFP) [28] were maintained in minimal essential medium (Sigma-Aldrich, St. Louis, MO) containing 10 fetal bovine serum (Atlanta Biologicals, Norcross, GA) and 100 IU/ml penicillin and streptomycin (Mediatech, Herndon, VA) at 37uC in a 5 CO2 incubator. Transient plasmid DNA transfection of HeLa cells was performed with jetPEITM (Polyplus transfection, 1655472 Illkirch, France), according to the manufacturer’s specifications using 0.5 mg DNA per 1 mL media. Transient co-transfection of HeLa cells with both plasmid DNA and siRNA was performed with jetPRIMETM (Polyplus transfection) according to the manufacturer’s specifications by using 150 ng of DNA and 10 pmol siRNA per 0.5 mL media. Transient siRNA transfections of siRNAs against Yif1A were performed using jetPRIMETM (Polyplus transfection) using 20 pmol siRNA per 0.5 mL media.Fluorescence microscopyAll images were obtained using a Yokagawa spinning disk confocal scanhead (Perkin Elmer Life and Analytical (��)-Imazamox supplier Sciences, Boston MA) mounted on an Axiovert 200 microscope (Carl Zeiss, Jena, Germany) with a 100X 1.4 16402044 numerical aperture (NA) objective (Carl Zeiss) and acquired using a 12-bit Orca ER digital camera (Hamamatsu Photonics, Hamamatsu City, Japan). Maximal value projections of sections at 0.3-mm spacing (5?/cell) were acquired using ImageJ (National Institutes of Health, Bethesda, MD).Quantification of efficiency of rescueFor each of our transgene replacement experiments, at least 100 cells were counted in three individual experiments and the data was calculated as the percentage of cells expressing the transgene that display ER whorls. In order to compare the different constructs over multiple sets of experiments, this percentage w.SiRNA-immune Yip1A transgene to rescue the whorled ER phenotype in knockdown cells [10], we carried out a systematic mutational analysis of nearly all residues in the protein; our goal being to determine those residues most important for its ER structural maintenance role.C-terminus. The HA-Yip1A D1-83 and D1-118 constructs were created using the PCR-based loop-out technique (Stratagene). All additional HA-Yip1A mutant constructs were created using QuikChange site directed mutagenesis PCR (Stratagene). siRNAs directed against Yif1A were created using a siRNA construction kit (Ambion) and previously published target sequences [13]. The control siRNA used in this study targets bovine p115 and does not affect p115 in HeLa cells [29].Antibodies, immunofluorescence and immunoblottingAntibodies used include mouse monoclonal antibody (mAb) against the HA-epitope (Sigma-Aldrich, St. Louis, MO); a rabbit polyclonal antibody (pAb) against Calnexin, a pAb against tubulin and a mAb against protein disulfide isomerase (PDI) (both Abcam, Cambridge, MA); the 9E10 mAb against the myc epitope [30]; a pAb against GPP130 (kindly provided by Dr. A. Linstedt, Carnegie Mellon University, Pittsburgh, PA). Fluorophore-conjugated secondary antibodies were from Zymed Laboratories (South San Francisco, CA)/Invitrogen (Carlsbad, CA). HeLa cells were typically analyzed 72 h post-transfection. Immunofluorescence procedures were as described previously [10]. Immunoblotting using a mouse mAb against the myc-epitope and a rabbit pAb against tubulin (Abcam), was performed on cells co-transfected with Yif1A siRNA and myc-Yif1A harvested from 60-mm dishes as described previously [31].Materials and Methods Cell culture and transfectionsHeLa cells stably expressing a GalNacT2-green fluorescent protein (GFP) [28] were maintained in minimal essential medium (Sigma-Aldrich, St. Louis, MO) containing 10 fetal bovine serum (Atlanta Biologicals, Norcross, GA) and 100 IU/ml penicillin and streptomycin (Mediatech, Herndon, VA) at 37uC in a 5 CO2 incubator. Transient plasmid DNA transfection of HeLa cells was performed with jetPEITM (Polyplus transfection, 1655472 Illkirch, France), according to the manufacturer’s specifications using 0.5 mg DNA per 1 mL media. Transient co-transfection of HeLa cells with both plasmid DNA and siRNA was performed with jetPRIMETM (Polyplus transfection) according to the manufacturer’s specifications by using 150 ng of DNA and 10 pmol siRNA per 0.5 mL media. Transient siRNA transfections of siRNAs against Yif1A were performed using jetPRIMETM (Polyplus transfection) using 20 pmol siRNA per 0.5 mL media.Fluorescence microscopyAll images were obtained using a Yokagawa spinning disk confocal scanhead (Perkin Elmer Life and Analytical Sciences, Boston MA) mounted on an Axiovert 200 microscope (Carl Zeiss, Jena, Germany) with a 100X 1.4 16402044 numerical aperture (NA) objective (Carl Zeiss) and acquired using a 12-bit Orca ER digital camera (Hamamatsu Photonics, Hamamatsu City, Japan). Maximal value projections of sections at 0.3-mm spacing (5?/cell) were acquired using ImageJ (National Institutes of Health, Bethesda, MD).Quantification of efficiency of rescueFor each of our transgene replacement experiments, at least 100 cells were counted in three individual experiments and the data was calculated as the percentage of cells expressing the transgene that display ER whorls. In order to compare the different constructs over multiple sets of experiments, this percentage w.