FIGURE 2.

Transgene expression of GFP-Ac45 mutant proteins specifically in the Xenopus melanotrope cells. A, overview of transgenes used to express Ac45 mutant proteins fused to GFP in the Xenopus melanotrope cells. B, sagital cryosections of transgenic Xenopus pituitaries. Transgenic Ac45 mutant/GFP expression was directly viewed under a fluorescence microscope (green). Sections were stained with an anti-POMC antibody (red) showing coexpression of GFP and POMC in the intermediate pituitary melanotrope cells. C, Western blot analysis of NIL lysates with an anti-GFP showing the expression levels of the respective transgene products. Ten percent of a total NIL lysate was analyzed. The lane with the Ac45ΔCS NIL lysate was taken from a separate Western blot. GFP*, stable GFP moiety, probably resulting from Ac45Nterm mutant fusion protein breakdown. D, endoproteolytic processing efficiencies of the Ac45wt and Ac45ΔC proteins are presented as the ratio of the amount of Ac45N-term relative to the amount of intact-Ac45 and the ratio of the amount of Ac45N-term relative to the amount of Ac45ΔC, respectively. Shown are the means ± S.E. (n = 4). Significant difference is indicated by ** (p < 0.01).