Expression of the Stp1 LMW-PTP and inhibition of protein CK2 display a cooperative effect on immunophilin Fpr3 tyrosine phosphorylation and <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> growth |
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Authors: | M?Marchetta T?Gamberi S?Sarno F?Magherini G?Raugei G?Camici L?A?Pinna Email author" target="_blank">A?ModestiEmail author |
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Institution: | (1) Dipartimento di Scienze Biochimiche, Università degli Studi di Firenze, Viale G. Morgagni 50, 50134 Firenze, Italy;(2) Dipartimento di Chimica Biologica, Università degli Studi di Padova, Padova, Italy |
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Abstract: | Although the yeast genome does not encode bona fide protein tyrosine kinases, tyrosine-phosphorylated proteins are numerous, suggesting that besides dual-specificity kinases, some Ser/Thr kinases are also committed to tyrosine phosphorylation in Saccharomyces cerevisiae. Here we show that blockage of the highly pleiotropic Ser/Thr kinase CK2 with a specific inhibitor synergizes with the overexpression of Stp1 low-molecular-weight protein tyrosine phosphatase (PTP) in inducing a severe growth-defective phenotype, consistent with a prominent role for CK2 in tyrosine phosphorylation in yeast. We also present in vivo evidence that immunophilin Fpr3, the only tyrosine-phosphorylated CK2 substrate recognized so far, interacts with and is dephosphorylated by Spt1. These data disclose a functional correlation between CK2 and LMW-PTPs, and suggest that reversible phosphorylation of Fpr3 plays a role in the regulation of growth rate and budding in S. cerevisiae.Received 15 January 2004; received after revision 20 February 2004; accepted 4 March 2004 |
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Keywords: | Tyrosine-phosphorylated proteins yeast tyrosine kinase immunophilin CK2 LMW-PTP |
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