Fig. 5.

Endogenous expression of Cab45, a Golgi lumenal-resident protein, in INS-1 cells. Cells were pulse labeled for 30 minutes with ³⁵S amino acids and chased continuously for 4 hours in the absence (−) or presence (+) of secretagogue (Stim). In duplicate, media (Med.) were collected and cells lysed, and the samples were then analyzed by sequential immunoprecipitation with mAb anti-Cab45 (lower panel) and polyclonal anti-insulin (upper panel). The Cab45 immunoprecipitates were further divided either for mock digestion (−) or endoglycosidase H (Endo H) digestion (+). At 4 hours of chase, Cab45 appears as two intracellular endo-H-resistant bands; the position of the 45 kDa molecular mass marker is shown.