Expression of the small tyrosine phosphatase (Stp1) in Saccharomyces cerevisiae: a study on protein tyrosine phosphorylation.
Small tyrosine phoshatase 1 (Stp1) is a Schizosaccharomyces pombe low-molecular-mass phosphotyrosine-phosphatase 50% identical to Saccharomyces cerevisiae Ltp1. In order to investigate the role of Stp1 in yeast, a mutant was generated having the characteristic of a dominant negative molecule. Changes in protein tyrosine phosphorylation in S. cerevisiae proteome in response to Stp1 or its dominant negative mutant expression were analyzed by high-resolution two-dimensional (2-D) electrophoresis. The most remarkable result is the modification by phosphorylation on tyrosine of several proteins involved in carbohydrate metabolism. Twelve proteins were identified on the basis of their positions in the anti-phosphotyrosine immunoblot of the 2-D electrophoresis. Ten of these present tyrosyl residues that are within the consensus sequence for protein kinase CK2 (casein kinase-2). These data open the possibility for the identification of Stp1 substrates in yeast and provide hints about the nature of tyrosine phosphorylating agents in yeast and in other organisms where bona fide tyrosine kinases are lacking.
Dipartimento di Scienze Biochemiche, Università di Firenze, Italy. modesti@scibio.unifi.it
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Modesti
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Bini
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Carraresi
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F
Magherini
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Liberatori
V
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Pallini
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Manao
L A
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Pinna
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Raugei
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Ramponi
D000180:Acrylic Resins; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003470:Culture Media; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D015870:Gene Expression; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010957:Plasmids; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development; D016622:Silver Staining; D014443:Tyrosine / Q000378:metabolism
D000180:Acrylic Resins; D003470:Culture Media; C016680:polyacrylamide gels; D014443:Tyrosine; D017027:Protein Tyrosine Phosphatases