FIGURE 4.

σ₁SR forms a complex with and co-localizes with σ₁R. A, co-immunoprecipitation of fluorescence-tagged σ₁SR and σ₁R in Neuro-2a cells. Extracts were immunoprecipitated (IP) with anti-eGFP antibody, and immunoprecipitates were immunoblotted (WB) with anti-σ₁R N-terminal cytosolic domain (upper panel) or with the C-terminal lumenal domain (lower panel) antibody. Cell extracts (Input) from Neuro-2a cells transfected with eGFP (lane 1), σ₁R-eGFP (lane 2), σ₁R-mCherry (lane 3), σ₁SR-eGFP (lane 4), or σ₁SR-mCherry (lane 5) constructs are shown as positive controls for σ₁R isoform immunoreactive bands. B and C, co-immunoprecipitation of σ₁Rs and IP₃Rs in Neuro-2a cells. Extracts were immunoprecipitated with anti-IP₃Rs (B) or anti-σ₁R N-terminal cytosolic domain (C) antibody, and immunoprecipitates were immunoblotted (WB) with anti-IP₃Rs (B) or anti-σ₁R N-terminal (C) antibody. As a positive control for σ₁Rs and IP₃Rs immunoreactive bands, cell extracts (Input) are shown from intact (lane 1) or σ₁R- (lane 2) or σ₁SR (lane 3)-transfected cells. D, confocal images showing co-localization of σ₁R-eGFP (green) and σ₁SR-mCherry (red) in Neuro-2a cells. Scale bar, 10 μm.