FIGURE 2.

Luminal calcium depletion impairs ER-to-Golgi transport of mannosidase II. NRK cells were treated with BFA for 45 min, with CPA or DMSO present for the final 15 min. After BFA removal (t = 0 on plot), CPA-treated cells recovered in calcium-free medium, whereas control cells recovered in normal medium. At the indicated times, cells were fixed and labeled for mannosidase II. A, arrival of mannosidase II in the Golgi area was quantified using the transport index algorithm as in Fig. 1. no BFA, cells received neither BFA nor CPA (blue triangle). B, a similar experiment except that return to the Golgi was quantified by measuring the area of mannosidase II-positive puncta. Single experiments were representative of at least three similar experiments; each value is a mean of ≥20 cells. Error bars, S.E.