title: The in vivo tyrosine phosphorylation level of yeast immunophilin Fpr3 is influenced by the LMW-PTP Ltp1.
abstract: Tyr-phosphorylation in Saccharomyces cerevisiae is essential in controlling the activity of MAP kinase regulating mating, pseudohyphal growth, and cell wall biosynthesis. Yeast serves as a model system for studying the biological function of many protein kinases and PTPs. Two LMW-PTP from yeast have been cloned, namely, Ltp1 from S. cerevisiae and Stp1 from Schizosaccharomyces pombe. The sequences of both enzymes are relatively similar to those of the mammalian LMW-PTP. Recently we showed that the yeast immunophilin Fpr3 interacts with Stp1 and its dephosphorylated state induces a growth defective phenotype. Here we show the phosphatase activity of Ltp1 on Fpr3 and we demonstrated that Tyr 184 is the residue phosphorylated on in vivo Fpr3. We also described the marked activation of Ltp1 by adenine in S. cerevisiae proteome and determined in vivo the influence of tyrosine phosphorylation on Fpr3 localization.
authors.affiliation: Dipartimento di Scienze Biochimiche, Università degli Studi di Firenze, Florence, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Magherini
authors.forename: Tania
authors.initials: T
authors.lastname: Gamberi
authors.forename: Paolo
authors.initials: P
authors.lastname: Paoli
authors.forename: Matilde
authors.initials: M
authors.lastname: Marchetta
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Biagini
authors.forename: Giovanni
authors.initials: G
authors.lastname: Raugei
authors.forename: Guido
authors.initials: G
authors.lastname: Camici
authors.forename: Giampietro
authors.initials: G
authors.lastname: Ramponi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Modesti
mesh_terms: D000225:Adenine / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal; D020104:Immunophilins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; C094972:LTP1 protein, S cerevisiae; D017027:Protein Tyrosine Phosphatases; C403327:FPR3 protein, S cerevisiae; D020104:Immunophilins; D000225:Adenine