Answer 5

Yes, there is a big problem. The cisternal progression model also requires vesicle transport as resident proteins must return to their normal position after their cisterna has moved on to the next trans-ward position. Thus vesicles carrying the galactose glycosyl transferase fron the trans-Golgi network to the trans cisterna could get into the mutant Golgi in the experimental cell. This may exsplain the odd results in the third row of the table in which about half of the label is as would be expected.