Figure 6.

Immunogold EM showing colocalization of EGFR and IP₃R1 in adrenal chromaffin cells. A and B show representative images from different preparations. Rat adrenal medullary chromaffin cells were double immunolabeled for the IP₃R1 (15 nm gold) and EGFR (10 nm gold) with the affinity purified IP₃R1-specific anti–rabbit antibody and anti–sheep EGFR antibody, respectively, as described in Online supplemental material. The gold particles labeling IP₃Rs are localized at the membranes of the secretory granules (SG), the ER, as well as at the PM. IP₃Rs at the ER juxtaposed to the PM are marked with arrowheads. Note that there are no nonspecific IP₃R1-labeling gold particles in mitochondria (M). The EGFRs (PM and ER, arrows) are primarily localized at the PM though it also appears in the ER. The IP₃R1 molecules that colocalize with the EGFR are marked with asterisks. The boundary of the PM is denoted with white dots for clarity. Bars, 200 nm.