1,721,010 research outputs found
Caratterizzazione di una nuova emoproteina del lievito S. cerevisiae espressa in E. coli.
No full textStudio di una putativa proteasi nucleare essenziale per la cellula di lievito e conservata dagli archebatteri all'uomo
No full textIn questo lavoro analizziamo alcune caratteristiche della proteina Kae1 di Saccharomyces cerevisiae. Essa è codificata da un gene essenziale ed è classificata come metallo-proteasi in base all’omologia di sequenza con una O-Sialo-Glico-Endo-Peptidasi di Pasteurella haemolytica. Kae1, che è localizzata prevalentemente nel nucleo, fa parte di un complesso multi proteico al quale appartiene anche la proteina piD261/Bud32. Quest’ultima è una Ser-Thr protein chinasi appartenente ad una sub famiglia, molto conservata, originatasi prima della divergenza tra Archebatteri ed Eucarioti. Il suo ruolo nel lievito è essenziale per la normale crescita cellulare e anche l’omologo umano, PRPK, è probabilmente coinvolto nel controllo della crescita cellulare, dal momento che è in grado di fosforilare p53 in corrispondenza di Ser-15, evento che porta al blocco del ciclo cellulare in seguito a danni al DNA. Anche la sequenza di Kae1 è molto conservata ed il suo omolog umano è chiamato OSGEP.
Qui mostreremo come PRPK e OSGEP siano omologhi funzionali delle corrispondenti proteine di lievito, grazie a saggi di complementazione fenotipica e anche che le due proteine PRPK e OSGEP sono in grado di interagire tra loro a supporto di un rilevante significato fisiologico di tale interazione. Dimostreremo inoltre che il mantenimento del motivo di legame al metallo HCIGH in Kae1 e OSGEP è correlato all’attività di tali proteine, dato che la sostituzione delle due istidine causa un fenotipo letale indistinguibile dalla delezione genica. Il nostro interesse è rivolto anche alla caratterizzazione del legame del metallo, data la particolarità della presenza inusuale di una cisteina nel motivo.
L’aspettativa è quella di dimostrare l’attività catalitica in vitro della putativa proteasi Kae1 isolata da lievito e di confermare il legame dello ione metallico, definendo i residui coinvolti in tale legame, attraverso saggi di assorbimento atomico sulle proteine, di tipo selvatico e mutanti, espresse in E. coli
UNDULY ENHANCED RESPONSE TO TOLVAPTAN IN A WOMAN SHOWING SYNDROME OF INAPPROPRIATE ANTIDIURETIC HORMONE SECRETION: AN INVESTIGATION OF POSSIBLE CAUSES
Full text linkObjective: To investigate possible causes of an excessive response to tolvaptan in a woman with syndrome of inappropriate antidiuretic hormone secretion (SIADH). Methods: A 32-year-old woman was admitted to our cardiologic unit 3 months after delivery for hypertension and severe hyponatremia (120 mEq/L). Two hyponatremic episodes had already been documented in her medical history. SIADH was diagnosed and treatment with tolvaptan, an arginine vasopressin (AVP) antagonist, was instituted. After the first 15-mg dose, excessive polyuria (1 L/ hour) and a rapid increase in serum sodium (13 mEq/L in 8 hours) occurred, so that therapy was stopped and restarted 2 days later at a reduced dose (5 mg). This level was effective and well tolerated. To explore the possible pharmacokinetic and pharmacodynamic mechanisms underlying the patient’s hyperresponsiveness, the following tests were carried out: (1) in vivo phenotyping of CYP3A4 activity, the cytochrome responsible for tolvaptan metabolism, with two probe drugs (omeprazole and dextromethorphan); and (2) search for mutations in genes involved in AVP signaling (AVP, V2R, AQP2, OXT)
Functional analysis of two genes encoding respectively a novel hemoglobin and a novel protein kinase of Saccharomyces cerevisiae
No full text
Analisi funzionale di un gene di Saccharomyces cerevisiae che codifica una protein chinasi a struttura particolare
No full textFunctional analysis of the YGR262c/Vsk1 gene encoding an atypical protein kinase essential for normal cell growth
No full textThe S.cerevisiae YGR262c gene, whose deletion confers to yeast cells a pleiotropic phenotype characterized, among other defects, by severe slow-growth, inability of homozygous diploids to enter sporulation and important alterations in cell wall structure, encodes a 261 residues protein kinase, piD261, now renamed Vsk1p (very small kinase 1), whose structurl homologues are present in a variety of organisms and whose function is unknown. We have previously demonstrated that the protein is a S/T kinase and here we show, by mutational analysis, that the invariant residues of protein kinase are all conserved in Vsk1p, but are embedded in a altered context, suggestive of unique mechanistic properties. The biological competence of the Vsk1p protein is correlated with its phosphotransferase activity, as the phenotype due to the VSK1 gene disruption is not, or partially, complemented by ectopic expression of Vsk1p point mutants which are catalitically inactive in vitro. However, the absence of the protein causes in the cell more dramatic effects thn its presence in a catalitically inactive form and this is possibly due to the failure to form protein complex(es) within the cell. In order to understand the actual role of the protein, we have started a search for protein(s) functionally associated with Vsk1p by the 2-hybrid approach. Two of the interacting proteins could be good candidates to correlate the function of this protein with the manifested phenotypes
Yeast complementation is sufficiently sensitive to detect the residual activity of ASL alleles associated with mild forms of argininosuccinic aciduria
No full textDemonstration that functional complementaiton in yeast can detect residual activity in hypomorphic ASL alleles and provide phenotype-genotype correlations for this disorder
Analysis of an 11.6 kb region from the right arm of chromosome VII of Saccharomyces cerevisiae between the RAD2 and MES1 genes reveals the presence of three new genes
No full textSequence analysis of an 11 628 bp DNA segment from the right arm of Saccharomyces cerevisiae chromosome VII
revealed the presence of the 5* end of the RAD2 gene, the MES1 gene and six open reading frames (ORFs) each
longer than 300 bp. Four of these ORFs are expressed genes, as indicated by transcript analysis. One of them,
YGR261c, which specifies a putative â-adaptine, corresponds to gene YKS5, which has recently been identified as a
suppressor of loss of casein kinase 1 function. The remaining three ORFs are new genes; of these, YGR260w encodes
a protein showing similarity to the S. cerevisiae allantoate permease and YGR262c specifies a putative protein kinase.
The sequence has been deposited in the EMBL data library under Accession Number Y07777. ? 1997 by John
Wiley & Sons, Ltd
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