To investigate the biogenesis of the yeast vacuole, we have sought novel marker proteins localized to the vacuolar membrane. Glycoproteins were prepared from vacuolar membrane vesicles by concanavalin A-Sepharose column chromatography and used to raise monoclonal antibodies. The antibodies obtained recognize several vacuolar proteins that have N-linked oligosaccharide chains. A set of the antibodies reacts with a vacuolar glycoprotein with a major molecular species of 72 kDa (vgp72), which appears to associate peripherally with the vacuolar membrane. The biosynthesis of vgp72 has been examined in detail by pulse-chase experiments and by analyses using various secretory mutants (sec18, sec7, and sec1) and a vacuolar protease mutant (pep4). vgp72 first appears in the endoplasmic reticulum as a 74-kDa species and is quickly modified in the Golgi apparatus to two distinct species: a 79-kDa form, and a heterogeneously glycosylated form (90-150 kDa). Subsequently, both species are proteolytically processed in the vacuole giving rise to a 72-kDa species as well as heavily glycosylated form. Thus, the biogenesis of vgp72 utilizes the early part of the secretory pathway as is the case of vacuolar soluble enzymes. A unique feature is that two species that are different in the extent of glycosylation appear to follow the same destination to the vacuolar membrane.

• PMID: 2110166
• PubMed
• PubTator

Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Nishikawa S, Umemoto N, Ohsumi Y, Nakano A, Anraku Y

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