Localization and transport of A-ALP and ALP in grd20 mutants. Strains in A and B were propagated at 30°C, pulsed for 10 min, and chased for the indicated times, and either A-ALP or ALP was immunoprecipitated and analyzed by SDS-PAGE and fluorography. (A) Analysis of strains SNY17 (GRD20), SBY7-7A (grd20::Tn3), and SBY4-10A (grd20-Δ1) carrying a CEN plasmid directing expression of A-ALP (pSN55). (B) Analysis of strains SNY17 (GRD20) and SBY7-7A (grd20::Tn3) carrying a CEN plasmid directing expression of ALP (pSN92). The positions at which precursor A-ALP (pA-ALP), mature A-ALP (mA-ALP), precursor ALP (pALP), mature ALP (mALP), and a breakdown product of mature ALP (*) migrate are indicated. (C) Strains LSY2 (GRD20 pep4Δ) and SBY6 (grd20::Tn3 pep4Δ) carrying pSN55 were fixed, spheroplasted, and costained with antibodies against A-ALP (upper panels) and Vma2p (lower panels). After subsequent treatment with fluorochrome-conjugated antibodies, the cells were viewed by differential interference contrast optics and by epifluorescence through filters specific for FITC and Texas Red.