Figure 3. Concomitant loss of both β3A and β3B is required to reduce adrenal SgII.

(A) Effect of individual AP-3 subunit mutations on SgII and AP-3 δ levels by immunofluorescence. Adrenal chromaffin cells from mocha (δ), pearl (β3A), β3B−/−, and control mice were stained with a rabbit polyclonal antibody to SgII and a mouse monoclonal antibody to AP-3 δ, followed by an anti-rabbit antibody conjugated to Alexa Fluor 488 and an anti-mouse antibody conjugated to Alexa Fluor 594. Representative confocal micrographs show the expected reduction in SgII and absence of AP-3 δ staining in mocha chromaffin cells, but unchanged SgII and AP-3 δ in both pearl and β3B−/− cells. (B) Non-chromaffin, fibroblast-like pearl cells present in the culture show a clear reduction in AP-3 δ. Scale bars indicate 5 µm. (C) The adrenal glands of pearl mice show a clear reduction in overall AP-3 levels, but unchanged SgII. (D) Adrenal glands of β3B−/− mice show no change in overall AP-3 or SgII levels. (E) Adrenal glands of double mutant pe/pe; β3B−/− mice show a clear reduction in SgII levels relative to age-matched C57BL/6 controls and pe/pe; β3B+/− controls. mocha adrenals show a reduction in SgII similar to that in pe/pe; β3B−/− mice. **p<0.001 relative to control by Dunnett's post-hoc test, n = 3. The data show mean values, and error bars indicate s.e.m.