Enzo Martegani

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The activity of adenylate cyclase in the yeast Saccharomyces cerevisiae is controlled by two G-protein systems, the Ras proteins and the Galpha protein Gpa2. Glucose activation of cAMP synthesis is thought to be mediated by Gpa2 and its G-protein-coupled receptor Gpr1. Using a sensitive GTP-loading assay for Ras2 we demonstrate that glucose addition also(More)
We have cloned the cDNA coding for the Rhodotorula gracilis D-amino acid oxidase (DAAO), an enzyme that performs with high catalytic efficiency biotechnologically relevant bioconversions, by PCR amplification. The first strand cDNA was synthesised from the total mRNA fraction isolated from R. gracilis cells grown under DAAO-inducing conditions. The R.(More)
Interesting challenges from metabolically engineered Saccharomyces cerevisiae cells arise from the opportunity to obtain yeast strains useful for the production of chemical(s). In this paper, we describe the accumulation of lactic acid in the culture medium of growing, engineered yeast cells expressing a mammalian lactate dehydrogenase gene (LDH-A). High(More)
Strains of Saccharomyces cerevisiae transformed with a multicopy expression vector bearing both the Escherichia coli beta-galactosidase gene under the control of the upstream activating sequence of the GAL1-10 genes and the GAL4 activator gene release part of beta-galactosidase in the growth medium. This release is due to cell lysis of the older mother(More)
In the yeast Saccharomyces cerevisiae genetic and biochemical evidence indicates that the product of the CDC25 gene activates the RAS/adenylyl cyclase/protein kinase A pathway by acting as a guanine nucleotide protein. Here we report the isolation of a mouse brain cDNA homologous to CDC25. The mouse cDNA, called CDC25Mm, complements specifically point(More)
The CDC25 gene product is a guanine nucleotide exchange factor for Ras proteins in yeast. Recently it has been suggested that the intracellular levels of guanine nucleotides may influence the exchange reaction. To test this hypothesis we measured the levels of nucleotides in yeast cells under different growth conditions and the relative amount of Ras2-GTP.(More)
The CDC25Mm gene codes for Ras-guanine nucleotide exchange factors. Four different full-length cDNA clones derived from the same gene and coding for proteins of different sizes that have in common the last 661 amino acids have been isolated from mouse brain. In order to investigate the expression of the products of this gene in different tissues we have(More)
In the manufacturing of baker's yeast by aerobic fed-batch systems, continuous assessment of the state of the process is necessary for regulating the flow rate (on/off) for growth medium addition. A new, simple method for the fed-batch yeast process has been developed. It is based on pH changes as a suitable parameter for regulating the feed of fresh(More)
RalGPS2 is a murine guanine nucleotide exchange factor of the RalGPS family; it contains a Cdc25-like GEF domain and does not exhibit a Ras-binding domain. The main characteristic of RalGPS2 is its pleckstrin homology (PH) domain, present at the C terminus, that preferentially binds phosphatidylinositol-4,5-biphosphate and in HEK 293 cells localized in(More)
Ras proteins are small GTPases playing a pivotal role in cell proliferation and differentiation. Their activation depends on the competing action of GTPase activating proteins and guanine nucleotide exchange factors (GEF). The properties of two dominant-negative mutants within the catalytic domains of the ras-specific GEF, CDC25(Mm), are described. In(More)