Figure 5. Shadowed images of nuclear envelopes from Sf9 cells expressing rat type 3 InsP₃R.

The nuclei were treated either with gold-labeled heparin (A) or with anti-type 3 InsP₃R followed by gold-labeled secondary antibody (B) followed by freeze-drying and rotary shadowing (see Methods). In both cases, the 5 nm gold particles are clearly associated with the InsP₃R-like structures, with the exception of 1 out of 11 gold particles in (A) (arrow). High magnification (insets) shows the gold particles mainly located in the central region of the structures. Note that the InsP₃R-like structures labeled by the gold particles have similar sizes but variable shapes and overall resemble the presumptive InsP₃R particles described above. The images are not as sharp as those in the previous figures because the technique used leaves some cellular debris associated with the shadowed replicas.