Novel Saccharomyces cerevisiae Gene, MRK1, Encoding a Putative Protein Kinase with Similarity to Mammalian Glycogen Synthase Kinase-3 and Drosophila Zeste-White3/Shaggy

1995 ◽  
Vol 208 (2) ◽  
pp. 728-734 ◽  
Author(s):  
T.A. Hardy ◽  
D. Wu ◽  
P.J. Roach
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Putative Protein ◽  
Putative Protein Kinase

scholarly journals Pho85p, a cyclin-dependent protein kinase, and the Snf1p protein kinase act antagonistically to control glycogen accumulation in Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (8) ◽  
pp. 4357-4365 ◽  
Author(s):  
D Huang ◽  
I Farkas ◽  
P J Roach
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Kinase Activity ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Mutant Gene ◽  
Glycogen Synthase Kinase ◽  
Partial Purification ◽  
Glycogen Accumulation ◽  
Dependent Protein

In Saccharomyces cerevisiae, nutrient levels control multiple cellular processes. Cells lacking the SNF1 gene cannot express glucose-repressible genes and do not accumulate the storage polysaccharide glycogen. The impaired glycogen synthesis is due to maintenance of glycogen synthase in a hyperphosphorylated, inactive state. In a screen for second site suppressors of the glycogen storage defect of snf1 cells, we identified a mutant gene that restored glycogen accumulation and which was allelic with PHO85, which encodes a member of the cyclin-dependent kinase family. In cells with disrupted PHO85 genes, we observed hyperaccumulation of glycogen, activation of glycogen synthase, and impaired glycogen synthase kinase activity. In snf1 cells, glycogen synthase kinase activity was elevated. Partial purification of glycogen synthase kinase activity from yeast extracts resulted in the separation of two fractions by phenyl-Sepharose chromatography, both of which phosphorylated and inactivated glycogen synthase. The activity of one of these, GPK2, was inhibited by olomoucine, which potently inhibits cyclin-dependent protein kinases, and contained an approximately 36-kDa species that reacted with antibodies to Pho85p. Analysis of Ser-to-Ala mutations at the three potential Gsy2p phosphorylation sites in pho85 cells implicated Ser-654 and/or Thr-667 in PHO85 control of glycogen synthase. We propose that Pho85p is a physiological glycogen synthase kinase, possibly acting downstream of Snf1p.

Analysis of RIM11, a yeast protein kinase that phosphorylates the meiotic activator IME1

1994 ◽  
Vol 14 (12) ◽  
pp. 7909-7919 ◽  
Author(s):  
K S Bowdish ◽  
H E Yuan ◽  
A P Mitchell
Keyword(s):  
Protein Kinase ◽  
Immune Complexes ◽  
Functional Relationship ◽  
Biological Function ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Yeast Protein ◽  
Yeast Genes

Many yeast genes that are essential for meiosis are expressed only in meiotic cells. Known regulators of early meiotic genes include IME1, which is required for their expression, and SIN3 and UME6, which prevent their expression in nonmeiotic cells. We report here the molecular characterization of the RIM11 gene, which we find is required for expression of several early meiotic genes. A close functional relationship between RIM11 and IME1 is supported by two observations. First, sin3 and ume6 mutations are epistatic to rim11 mutations; prior studies have demonstrated their epistasis to ime1 mutations. Second, overexpression of RIM11 can suppress an ime1 missense mutation (ime1-L321F) but not an ime1 deletion. Sequence analysis indicates that RIM11 specifies a protein kinase related to rat glycogen synthase kinase 3 and the Drosophila shaggy/zw3 gene product. Three partially defective rim11 mutations alter residues involved in ATP binding or catalysis, and a completely defective rim11 mutation alters a tyrosine residue that corresponds to the site of an essential phosphorylation for glycogen synthase kinase 3. Immune complexes containing a hemagglutinin (HA) epitope-tagged RIM11 derivative, HA-RIM11, phosphorylate two proteins, p58 and p60, whose biological function is undetermined. In addition, HA-RIM11 immune complexes phosphorylate a functional IME1 derivative but not the corresponding ime1-L321F derivative. We propose that RIM11 stimulates meiotic gene expression through phosphorylation of IME1.

scholarly journals Multiple mechanisms for the phosphorylation of C-terminal regulatory sites in rabbit muscle glycogen synthase expressed in COS cells

1996 ◽  
Vol 313 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Alexander V. SKURAT ◽  
Peter J. ROACH
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Rabbit Muscle ◽  
Cos Cells ◽  
Additional Mutation ◽  
Regulatory Sites

Glycogen synthase can be inactivated by sequential phosphorylation at the C-terminal residues Ser652 (site 4), Ser648 (site 3c), Ser644 (site 3b) and Ser640 (site 3a) catalysed by glycogen synthase kinase-3. In vitro, glycogen synthase kinase-3 action requires that glycogen synthase has first been phosphorylated at Ser656 (site 5) by casein kinase II. Recently we demonstrated that inactivation is linked only to phosphorylation at site 3a and site 3b, and that, in COS cells, modification of these sites can occur by alternative mechanisms independent of any C-terminal phosphorylations [Skurat and Roach (1995) J. Biol. Chem. 270, 12491-12497]. To address these mechanisms multiple Ser → Ala mutations were introduced in glycogen synthase such that only site 3a or site 3b remained intact. Additional mutation of Arg637 → Gln eliminated phosphorylation of site 3a, indicating that Arg637 may be important for recognition of site 3a by its corresponding protein kinase(s). Similarly, additional mutation of Pro645 → Ala eliminated phosphorylation of site 3b, indicating a possible involvement of ‘proline-directed’ protein kinase(s). Mutation of Arg637 alone did not activate glycogen synthase as expected from the loss of phosphorylation at site 3a. Rather, mutation of both Arg637 and the Ser → Ala substitution at site 3b was required for substantial activation. The results suggest that sites 3a and 3b can be phosphorylated independently of one another by distinct protein kinases. However, phosphorylation of site 3b can potentiate phosphorylation of site 3a, by an enzyme such as glycogen synthase kinase-3.

scholarly journals Glycogen Synthase Kinase 3 Phosphorylates Hypoxia-Inducible Factor 1α and Mediates Its Destabilization in a VHL-Independent Manner

2007 ◽  
Vol 27 (9) ◽  
pp. 3253-3265 ◽  
Author(s):  
Daniela Flügel ◽  
Agnes Görlach ◽  
Carine Michiels ◽  
Thomas Kietzmann
Keyword(s):  
Protein Kinase ◽  
Metabolic Diseases ◽  
Glycogen Synthase ◽  
Protein Kinase B ◽  
Hypoxia Inducible Factor ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Independent Manner ◽  
Von Hippel Lindau ◽  
Gsk 3Β

ABSTRACT Hypoxia-inducible transcription factor 1α (HIF-1α) is a key player in the response to hypoxia. Additionally, HIF-1α responds to growth factors and hormones which can act via protein kinase B (Akt). However, HIF-1α is not a direct substrate for this kinase. Therefore, we investigated whether the protein kinase B target glycogen synthase kinase 3 (GSK-3) may have an impact on HIF-1α. We found that the inhibition or depletion of GSK-3 induced HIF-1α whereas the overexpression of GSK-3β reduced HIF-1α. These effects were mediated via three amino acid residues in the oxygen-dependent degradation domain of HIF-1α. In addition, mutation analyses and experiments with von Hippel-Lindau (VHL)-defective cells indicated that GSK-3 mediates HIF-1α degradation in a VHL-independent manner. In line with these observations, the inhibition of the proteasome reversed the GSK-3 effects, indicating that GSK-3 may target HIF-1α to the proteasome by phosphorylation. Thus, the direct regulation of HIF-1α stability by GSK-3 may influence physiological processes or pathophysiological situations such as metabolic diseases or tumors.

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