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51.
52.
Cullin 4 (Cul4), a member of the evolutionally conserved cullin protein family, serves as a scaffold to assemble multisubunit ubiquitin E3 ligase complexes. Cul4 interacts with the Ring finger-containing protein ROC1 through its C-terminal cullin domain and with substrate recruiting subunit(s) through its N-terminus. Previous studies have demonstrated that Cul4 E3 ligase ubiquitylates key regulators in cell cycle control and mediates their degradation through the proteasomal pathway, thus contributing to genome stability. Recent studies from several groups have revealed that Cul4 E3 ligase can target histones for ubiquitylation, and importantly, ubiquitylation of histones may facilitate the cellular response to DNA damage. Therefore, histone ubiquitylation by Cul4 E3 ligase constitutes a novel mechanism through which Cul4 regulates chromatin function and maintains genomic integrity. We outline these studies and suggest that histone ubiquitylation might play important roles in Cul4-regualted chromatin function including the cellular response to DNA damage and heterochromatin gene silencing. 相似文献
53.
Yvet E Noordman Patrick AM Jansen Wiljan JAJ Hendriks 《Journal of molecular signaling》2006,1(1):1-11
Background
Spatio-temporal control of extracellular signal-regulated kinase (ERK) activity, a critical determinant of the cell's response to growth factors, requires timely dephosphorylation of its regulatory tyrosine and/or threonine residue by MAPK phosphatases. We studied the physiological role of kinase interaction motif (KIM)-containing protein tyrosine phosphatases (PTPs) in the control of EGF- and NGF-induced ERK activity in neuroendocrine PC12 cells.Results
We found a single KIM-containing PTP to be endogenously expressed in rat PC12 cells: the transmembrane PTPRR isoform termed PCPTP1. Protein knock-down of PCPTP1, or fourfold overexpression of its mouse orthologue, PTPBR7, left EGF- and NGF-induced ERK1/2 activity in PC12 cells unaltered. Ectopic expression of cytosolic PTPRR isoforms, however, resulted in reduced EGF-induced ERK1/2 activity, an effect that was dependent on the phosphatase activity and the KIM-domain of these PTPs.Conclusion
The finding that robust changes in tyrosine-specific MAPK phosphatase expression levels have minor effects on temporal ERK1/2 activity control in PC12 cells suggests that dual-specificity MAPK phosphatases may act as major regulators of growth factor-induced ERK1/2 signaling in these cells. 相似文献54.
Albart Coster John WM Bastiaansen Mario PL Calus Johan AM van Arendonk Henk Bovenhuis 《遗传、选种与进化》2010,42(1):9
The objective of this simulation study was to compare the effect of the number of QTL and distribution of QTL variance on the accuracy of breeding values estimated with genomewide markers (MEBV). Three distinct methods were used to calculate MEBV: a Bayesian Method (BM), Least Angle Regression (LARS) and Partial Least Square Regression (PLSR). The accuracy of MEBV calculated with BM and LARS decreased when the number of simulated QTL increased. The accuracy decreased more when QTL had different variance values than when all QTL had an equal variance. The accuracy of MEBV calculated with PLSR was affected neither by the number of QTL nor by the distribution of QTL variance. Additional simulations and analyses showed that these conclusions were not affected by the number of individuals in the training population, by the number of markers and by the heritability of the trait. Results of this study show that the effect of the number of QTL and distribution of QTL variance on the accuracy of MEBV depends on the method that is used to calculate MEBV. 相似文献
55.
YeeI, a novel protein involved in modulation of the activity of the glucose-phosphotransferase system in Escherichia coli K-12
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Becker AK Zeppenfeld T Staab A Seitz S Boos W Morita T Aiba H Mahr K Titgemeyer F Jahreis K 《Journal of bacteriology》2006,188(15):5439-5449
The membrane-bound protein EIICB(Glc) encoded by the ptsG gene is the major glucose transporter in Escherichia coli. This protein is part of the phosphoenolpyruvate:glucose-phosphotransferase system, a very important transport and signal transduction system in bacteria. The regulation of ptsG expression is very complex. Among others, two major regulators, the repressor Mlc and the cyclic AMP-cyclic AMP receptor protein activator complex, have been identified. Here we report identification of a novel protein, YeeI, that is involved in the regulation of ptsG by interacting with Mlc. Mutants with reduced activity of the glucose-phosphotransferase system were isolated by transposon mutagenesis. One class of mutations was located in the open reading frame yeeI at 44.1 min on the E. coli K-12 chromosome. The yeeI mutants exhibited increased generation times during growth on glucose, reduced transport of methyl-alpha-d-glucopyranoside, a substrate of EIICB(Glc), reduced induction of a ptsG-lacZ operon fusion, and reduced catabolite repression in lactose/glucose diauxic growth experiments. These observations were the result of decreased ptsG expression and a decrease in the amount of EIICB(Glc). In contrast, overexpression of yeeI resulted in higher expression of ptsG, of a ptsG-lacZ operon fusion, and of the autoregulated dgsA gene. The effect of a yeeI mutation could be suppressed by introducing a dgsA deletion, implying that the two proteins belong to the same signal transduction pathway and that Mlc is epistatic to YeeI. By measuring the surface plasmon resonance, we found that YeeI (proposed gene designation, mtfA) directly interacts with Mlc with high affinity. 相似文献
56.
Boos M Zorn T Koch A Le Maho Y Robin JP 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》2000,323(2):183-193
Measuring body lipids and proteins of wild animals such as mallards is essential to determine the impact of the environment on their body condition. A major difficulty, however, is that biochemical analysis of carcass is tedious and therefore cannot be applied at a large scale. The main objective of this study was therefore to find out if simple measurements can be used as indices of total body lipids and proteins. Four classes of lipid and protein indices, derived on a 'source' group, were defined according to their complexity and condition of application (field or laboratory). Accuracy of the indices was evaluated on an independent group, of which the body composition calculated from indices was compared to carcass analysis. In live birds, body mass was an accurate and convenient predictor for both lipid and protein masses. If carcasses are available, extensive analysis provides a higher accuracy for body lipids only. This can be simply obtained through multiple regressions using abdominal fat mass and/or dry body mass. 相似文献
57.
The precise duplication of the eukaryotic genome is accomplished by carefully coordinating the loading and activation of the replicative DNA helicase so that each replication origin is unwound and assembles functional bi-directional replisomes just once in each cell cycle. The essential Minichromosome Maintenance 2-7 (Mcm2-7) proteins, comprising the core of the replicative DNA helicase, are first loaded at replication origins in an inactive form. The helicase is then activated by recruitment of the Cdc45 and GINS proteins into a holo-helicase known as CMG (Cdc45, Mcm2-7, GINS). These steps are regulated by multiple mechanisms to ensure that Mcm2-7 loading can only occur during G1 phase, whilst activation of Mcm2-7 cannot occur during G1 phase. Here we review recent progress in understanding these critical reactions focusing on the mechanism of helicase loading and activation. 相似文献
58.
Ryanne JM Lemmens Annick AA Timmermans Yvonne JM Janssen-Potten Rob JEM Smeets Henk AM Seelen 《BMC neurology》2012,12(1):1-17
Background
Loss of arm-hand performance due to a hemiparesis as a result of stroke or cerebral palsy (CP), leads to large problems in daily life of these patients. Assessment of arm-hand performance is important in both clinical practice and research. To gain more insight in e.g. effectiveness of common therapies for different patient populations with similar clinical characteristics, consensus regarding the choice and use of outcome measures is paramount. To guide this choice, an overview of available instruments is necessary. The aim of this systematic review is to identify, evaluate and categorize instruments, reported to be valid and reliable, assessing arm-hand performance at the ICF activity level in patients with stroke or cerebral palsy.Methods
A systematic literature search was performed to identify articles containing instruments assessing arm-hand skilled performance in patients with stroke or cerebral palsy. Instruments were identified and divided into the categories capacity, perceived performance and actual performance. A second search was performed to obtain information on their content and psychometrics.Results
Regarding capacity, perceived performance and actual performance, 18, 9 and 3 instruments were included respectively. Only 3 of all included instruments were used and tested in both patient populations. The content of the instruments differed widely regarding the ICF levels measured, assessment of the amount of use versus the quality of use, the inclusion of unimanual and/or bimanual tasks and the inclusion of basic and/or extended tasks.Conclusions
Although many instruments assess capacity and perceived performance, a dearth exists of instruments assessing actual performance. In addition, instruments appropriate for more than one patient population are sparse. For actual performance, new instruments have to be developed, with specific focus on the usability in different patient populations and the assessment of quality of use as well as amount of use. Also, consensus about the choice and use of instruments within and across populations is needed. 相似文献59.
60.