Heterogeneous glycosylation of the EXG1 gene product accounts for the two extracellular exo-beta-glucanases of Saccharomyces cerevisiae.

Two exo-beta-glucanases of glycoprotein nature can be detected in culture supernatants of Saccharomyces cerevisiae cells. These exo-beta-glucanases show different Mr values and kinetic properties, although they are immunologically related. Their carbohydrate content and the electrophoretic mobility of both endoglycosidase H-treated exo-beta-glucanases suggest that they share the same protein fraction. Studies at genetic level relate the production of both extracellular exo-beta-glucanases with the expression of a single-copy gene in S. cerevisiae. Expression of this gene in another yeast, Schizosaccharomyces pombe, demonstrates that it codes for a protein with exo-beta-glucanase activity whose heterogeneous N-glycosylation accounts for both extracellular exo-beta-glucanases of S. cerevisiae.