Deletion of the β subunits does not affect transport pathways to the vacuole. (A) CPY transport in wild-type (GPY 6210) and apl1Δ apl2Δ apl6Δ (GPY 1783–21C) cells was analyzed by pulse–chase immunoprecipitation. Cells were grown and labeled at 30°C for 10 min followed by a chase period of 30 min. At the designated times, culture supernatant (E) and cell lysate (I) were prepared, CPY was immunoprecipitated and analyzed by SDS-PAGE. Endoplasmic reticulum-modified (p1), Golgi-modified (p2), and mature (M) forms are indicated. (B) ALP transport in wild-type (GPY6210), apl6Δ (1783-25A), and apl1Δ apl2Δ apl6Δ (GPY 1783-21C) cells was analyzed using the pulse–chase regimen described in A. ALP was immunoprecipitated from cell lysates at the designated chase times and analyzed by SDS-PAGE. Precursor and mature forms are indicated as well as a degradation product (*). (C) API maturation in (GPY 6210) and apl1Δ apl2Δ apl6Δ (GPY 1783-21C) cells by pulse–chase immunoprecipitation. API was immunoprecipitated from cell lysates at the designated chase times and analyzed by SDS-PAGE. Precursor and mature forms are indicated.