Figure 6.

Truncation study of P domain. Subcellular localization (A) and expression and secretion assessed by Western blotting (B) of PC3T594–EGFP (a), PC3G593–EGFP (b), Sig–PdD616–EGFP (c), Sig–PdT594–EGFP (d) and Sig–PdG593–EGFP (e) in βTC3 cells are shown. PC3T594–EGFP and PC3G593–EGFP are C-terminally truncated forms of PC3D616–EGFP (active control). Among these truncations, only lack of T594 in PC3 (b) resulted in ER retention. Sig–PdD616–EGFP could be sorted into Golgi and secreted into the medium, where it was detected as a 45-kDa band; however, in the absence of the catalytic domain, truncation after G593 of the P domain (e) did not prevent secretion. (Magnification: A, ×800.)