Two exo-β-glucanases of glycoprotein nature can be detected in culture supernatants of Saccharomyces cerevisiae cells. These exo-β-glucanases show different M r values and kinetic properties, although they are immunologically related. Their carbohydrate content and the electrophoretic mobility of both endoglycosidase H-treated exo-β-glucanases suggest that they share the same protein fraction. Studies at genetic level relate the production of both extracellular exo-β-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-β-glucanase activity whose heterogeneous N-glycosylation accounts for both extracellular exo-β-glucanases of S. cerevisiae.
