Figure 1.

Depletion of Ykt6p results in Golgi and post-Golgi membrane transport blocks. (A) Ykt6p Western blot of whole cell extracts of GAL1-YKY6 strains (ARY1) grown in galactose and glucose media. The cultures were diluted when they reached an optical density of ∼1 to keep cells growing in logarithmic phase. Cells (10 OD) were collected at the indicated times and equivalent cell extracts were analyzed by SDS-PAGE and immunoblotting with antiserum against Ykt6p. (B) Strains were pulse labeled with [³⁵S]methionine for 10 min at 30°C and chased for 45 min, and CPY was immunoprecipitated from intracellular (I) and extracellular (E) fractions and analyzed by SDS-PAGE and autoradiography. (C) Strains were labeled and chased as described above, and ALP was immunoprecipitated and the protein resolved by SDS-PAGE, and visualized by autoradiography. PEP4-dependent cleavage of proALP (pALP) results in the formation of the mature form (mALP) as well as an additional commonly observed degradation product (*).