Figure 1.

I₂^B promotes vacuole fusion. (A) Yeast cytosol was subjected to successive steps of DEAE-cellulose, SP-Sepharose Fast Flow, Sephacryl S-300HR chromatography, and chromatofocusing. Alternate fractions (200 μl) of the latter were analyzed by high-Tris SDS/PAGE followed by staining with Coomassie brilliant blue R. Positions of molecular weight markers are shown on the right and of I₂^B on the left. (B) The pH of alternate fractions and their ability to drive vacuole fusion in the presence of limiting amounts of Sec18p was determined.