Figure 2.

Pulse-chase experiments to follow the intracellular transport of CPY and ALP. (A) Wild-type cells (YPH499, WT), integrants of wild-type ARF1 (NYY0, Δarf2), and arf1 ts mutant alleles (arf1-11–arf1-18) were grown to an early log phase at 23°C, preincubated at 37°C for 30 min, labeled with Tran³⁵S-label for 4 min, and chased. Aliquots were withdrawn at the indicated times, subjected to sampling for immunoprecipitation with the anti-CPY antiserum, and visualized by SDS-PAGE and fluorography. p1, ER-precursor form; p2, Golgi-precursor form; m, mature form. Quantitation of CPY processing at the 60-min chase point is indicated as the percentage of the total. (B) Wild-type, arf1-13 and arf1-14 cells were subjected to a similar but more precise pulse-chase and immunoprecipitation experiment with anti-ALP and anti-CPY antisera. The migration positions of the precursor (pro) and mature (m) forms of ALP are also indicated.