J. T. Postmus

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The specific pH values of cellular compartments affect virtually all biochemical processes, including enzyme activity, protein folding and redox state. Accurate, sensitive and compartment-specific measurements of intracellular pH (pHi) dynamics in living cells are therefore crucial to the understanding of stress response and adaptation. We used the(More)
Realistic quantitative models require data from many laboratories. Therefore, standardization of experimental systems and assay conditions is crucial. Moreover, standards should be representative of the in vivo conditions. However, most often, enzyme-kinetic parameters are measured under assay conditions that yield the maximum activity of each enzyme. In(More)
Here we describe the cloning of the human Achaete Scute Homologue 2 (HASH2) gene, officially designated ASCL2 (Achaete Scute complex like 2), a homologue of the Drosophila Achaete and Scute genes. In mouse, this gene is imprinted and maps to chromosome 7. We mapped the human homologue close to IGF2 and H19 at 11p15.5, the human region syntenic with mouse(More)
Qualitative phenotypic changes are the integrated result of quantitative changes at multiple regulatory levels. To explain the temperature-induced increase of glycolytic flux in fermenting cultures of Saccharomyces cerevisiae, we quantified the contributions of changes in activity at many regulatory levels. We previously showed that a similar temperature(More)
A major challenge in systems biology lies in the integration of processes occurring at different levels, such as transcription, translation, and metabolism, to understand the functioning of a living cell in its environment. We studied the high temperature-induced glycolytic flux increase in Saccharomyces cerevisiae and investigated the regulatory mechanisms(More)
Defined serum-free conditions have great conceptual advantages for the biological safety and standardization of clinical gene transfer into hematopoietic stem cells. In the only study reported to date, Sekhar et al. achieved low serum conditions by a complex concentration procedure of a retroviral supernatant initially containing 10% fetal bovine serum. The(More)
To adapt to changes in the environment, cells have to dynamically alter their phenotype in response to, for instance, temperature and oxygen availability. Interestingly, mitochondrial function in Saccharomyces cerevisiae is inherently temperature sensitive; above 37 °C, yeast cells cannot grow on respiratory carbon sources. To investigate this phenomenon,(More)
We investigated the interaction between FtsZ and the cytoplasmic membrane using inside-out vesicles. Comparison of the trypsin accessibility of purified FtsZ and cytoplasmic membrane-bound FtsZ revealed that the protruding loop between helix 6 and helix 7 is protected from trypsin digestion in the latter. This hydrophobic loop contains an arginine residue(More)
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Sluijsmans and Kolenbrander developed a simple model to describe the availability of animal manure, assuming a readily available, an easily decomposable and a slowly decomposable N fraction. We tested this model on data from an experiment in which farmyard manure had been applied for eleven successive years to silage maize [Zea mays L.] grown on a light(More)