2,400 research outputs found
Regulation of the human tRNase ZS gene expression
AbstractThere are two types of tRNA 3′ processing endoribonucleases (tRNase Z): a short form (tRNase ZS) and a long form (tRNase ZL). Although the human genome contains both genes, little is known about the physiological role of tRNase ZS. We found that the human tRNase ZS gene expression appears to be post-transcriptionally regulated. Additionally, analyses for cis-regulatory elements for the tRNase ZS gene transcription suggested that transcription factors that bind to five different sites on the promoter work together to potentiate the transcription initiation. Furthermore, we found that tRNase ZS is predominantly present in the cytosol and hardly in the nucleus
Understanding Rad51 function is a prerequisite for progress in cancer research
The human protein Rad51 is double-edged in cancer contexts: on one hand, preventing tumourigenesis by eliminating potentially carcinogenic DNA damage and, on the other, promoting tumours by introducing new mutations. Understanding mechanistic details of Rad51 in homologous recombination (HR) and repair could facilitate design of novel methods, including CRISPR, for Rad51-targeted cancer treatment. Despite extensive research, however, we do not yet understand the mechanism of HR in sufficient detail, partly due to complexity, a large number of Rad51 protein units being involved in the exchange of long DNA segments. Another reason for lack of understanding could be that current recognition models of DNA interactions focus only on hydrogen bond-directed base pair formation. A more complete model may need to include, for example, the kinetic effects of DNA base stacking and unstacking (\u27longitudinal breathing\u27). These might explain how Rad51 can recognize sequence identity of DNA over several bases long stretches with high accuracy, despite the fact that a single base mismatch could be tolerated if we consider only the hydrogen bond energy. We here propose that certain specific hydrophobic effects, recently discovered destabilizing stacking of nucleobases, may play a central role in this context for the function of Rad51
The Role of Alpha-Dystrobrevin in Striated Muscle
Muscular dystrophies are a group of diseases that primarily affect striated muscle and are characterized by the progressive loss of muscle strength and integrity. Major forms of muscular dystrophies are caused by the abnormalities of the dystrophin glycoprotein complex (DGC) that plays crucial roles as a structural unit and scaffolds for signaling molecules at the sarcolemma. α-Dystrobrevin is a component of the DGC and directly associates with dystrophin. α-Dystrobrevin also binds to intermediate filaments as well as syntrophin, a modular adaptor protein thought to be involved in signaling. Although no muscular dystrophy has been associated within mutations of the α-dystrobrevin gene, emerging findings suggest potential significance of α-dystrobrevin in striated muscle. This review addresses the functional role of α-dystrobrevin in muscle as well as its possible implication for muscular dystrophy
Fluorescence study of the RecA-dependent proteolysis of LexA, the represser of the SOS system in Escherichia coli
AbstractThe fluorescence of the LexA protein, the common repressor of the SOS system in Escherichia coli decreases by about 30% upon incubation with the Ree A protein, and its cofactors ATP [or its non-hydroly sable analogue adenosine-5'-O-(3-thiotriphosphate), ATPγS] Mg2+ and single-stranded DNA. In the absence of any one of these elements required for the RecA-dependent proteolysis of LexA, this fluorescence change was not observed. The final fluorescence change depends only upon the concentration of LexA regardless of that of RecA. The time course of the fluorescence decrease corresponds well with the kinetics of the decrease of intact LexA protein and the increase of its 2 proteolytic fragments as determined by SDS-polyacrylamide gel electrophoresis. These results allow us to use the fluorescence change as a signal for a detailed kinetic analysis. The velocity of the proteolysis (d[LexA]/dt) is proportional to the concentration of LexA and RecA indicating that the formation of the LexA-RecA complex is the limiting step
Higgs response and pair condensation energy in superfluid nuclei
The pairing correlation in nuclei causes a characteristic excitation, known
as the pair vibration, which is populated by the pair transfer reactions. Here
we introduce a new method of characterizing the pair vibration by employing an
analogy to the Higgs mode, which emerges in infinite superconducting/superfluid
systems as a collective vibrational mode associated with the amplitude
oscillation of the Cooper pair condensate. The idea is formulated by defining a
pair-transfer probe, the Higgs operator, and then describing the linear
response and the strength function to this probe. We will show that the pair
condensation energy in nuclei can be extracted with use of the strength sum and
the static polarizability of the Higgs response. In order to demonstrate and
validate the method, we perform for Sn isotopes numerical analysis based the
quasi-particle random phase approximation to the Skyrme-Hartree-Fock-Bogoliubov
model. We discuss a possibility to apply this new scheme to pair transfer
experiment.Comment: 31 pages, 9 figure
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