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Glucose‐induced degradation of yeast fructose‐1,6‐bisphosphatase requires additional triggering events besides protein phosphorylation
Author(s) -
Lamponi Sandro,
Galassi Carla,
Tortora Paolo,
Guerritore Andrea
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80703-2
Subject(s) - phosphorylation , proteolysis , adenylate kinase , fructose 1,6 bisphosphatase , biochemistry , protein kinase a , protein phosphorylation , phosphorylation cascade , biology , proteolytic enzymes , enzyme , chemistry
Glucose addition to yeast cells stimulates a CAMP overshoot with concomitant activation of cAMP‐dependent protein kinase, which in turn rapidly phosphorylates fructose‐ 1,6‐bisphosphatase. The phosphorylated enzyme subsequently undergoes a slow proteolytic breakdown. Also, it has been proposed that phosphorylation represents the mechanism that initiates proteolysis. Here we present experiments carried out on a yeast mutant defective in adenylate cyclase [(1982) Proc. Natl. Acad. Sci. USA 79, 2355‐2359] in which extracellular CAMP triggers full enzyme phosphorylation but a scanty proteolysis, whereas glucose plus cAMP provoke both phosphorylation and complete proteolytic breakdown. Thus, besides a glucose‐induced cAMP peak, which results in enzyme phosphorylation, other effects evoked by the sugar are indispensable for its proteolytic degradation.