Search results for "Ligo"
showing 10 items of 1427 documents
Mutational analysis of the cysteine residues in the hepatitis B virus small envelope protein.
1993
The small envelope protein of hepatitis B virus is the major component of the viral coat and is also secreted from cells as a 20-nm subviral particle, even in the absence of other viral proteins. Such empty envelope particles are composed of approximately 100 copies of this polypeptide and host-derived lipids and are stabilized by extensive intermolecular disulfide cross-linking. To study the contribution of disulfide bonds to assembly and secretion of the viral envelope, single and multiple mutants involving all 14 cysteines in HepG2 and COS-7 cells were analyzed. Of the six cysteines located outside the region carrying the surface antigen, Cys-48, Cys-65, and Cys-69 were each found to be …
Precision wormlike nanoadjuvant governs potency of vaccination
2021
It remains unclear how the precise length of one-dimensional nanovehicles influences the characters of vaccination. Here, a unimolecular nanovehicle with tailored size and aspect ratio (AR) is applied to deliver CpG oligodeoxynucleotide, a Toll-like receptor (TLR) 9 agonist, as an adjuvant of recombinant hepatitis B virus surface antigen (rHBsAg), for treating chronic hepatitis B (CHB). Cationic nanovehicles with fixed width (ca. 45 nm) but varied length (46 nm-180 nm), AR from 1 to 4, are prepared through controlled polymerization and are loaded with CpG by electrostatic interaction. We reveal that the nanoadjuvant with AR = 2 shows the highest retention in proximal lymph nodes. Importantl…
Sequence-Specific Repression of Cotranslational Translocation of the Hepatitis B Virus Envelope Proteins Coincides with Binding of Heat Shock Protein…
1997
AbstractThe large L envelope protein of the hepatitis B virus has the peculiar capacity to adopt two transmembrane topologies. The N-terminal preS domain of L initially remains in the cytosol while the S domain is cotranslationally inserted into the endoplasmic reticulum membrane. The preS region of about half of the L molecules is posttranslationally translocated to the lumenal space. We now demonstrate that the repression of cotranslational translocation of preS is conferred by a preS1-specific sequence. By analysis of L deletion mutants, the cytosolic anchorage determinant was mapped to amino acid sequence 70 to 94 of L. The intrinsic potential of this determinant to suppress cotranslati…
Inhibition of ubiquitin-dependent proteolysis by a synthetic glycine-alanine repeat peptide that mimics an inhibitory viral sequence.
2002
AbstractThe glycine–alanine repeat (GAr) of the Epstein–Barr virus nuclear antigen-1 is a cis-acting transferable element that inhibits ubiquitin/proteasome-dependent proteolysis in vitro and in vivo. We have here examined the effect of a synthetic 20-mer GAr oligopeptide on the degradation of iodinated or biotin labeled lysozyme in a rabbit reticulocyte lysates in vitro assay. Micromolar concentrations of the GA-20 peptide inhibited the hydrolysis of lysozyme without significant effect on ubiquitination. Addition of the peptide did not inhibit the hydrolysis of fluorogenic substrate by purified proteasomes and did not affect the ubiquitination of lysozyme. An excess of the peptide failed t…
Activation of oligodendroglial Fyn kinase enhances translation of mRNAs transported in hnRNP A2-dependent RNA granules.
2008
Central nervous system myelination requires the synthesis of large amounts of myelin basic protein (MBP) at the axon–glia contact site. MBP messenger RNA (mRNA) is transported in RNA granules to oligodendroglial processes in a translationally silenced state. This process is regulated by the trans-acting factor heterogeneous nuclear ribonucleoprotein (hnRNP) A2 binding to the cis-acting A2 response element (A2RE). Release of this repression of MBP mRNA translation is thus essential for myelination. Mice deficient in the Src family tyrosine kinase Fyn are hypomyelinated and contain reduced levels of MBP. Here, we identify hnRNP A2 as a target of activated Fyn in oligodendrocytes. We show that…
Heterogeneous nuclear ribonucleoprotein (hnRNP) F is a novel component of oligodendroglial RNA transport granules contributing to regulation of myeli…
2011
Myelin basic protein (MBP) is a major component of central nervous system (CNS) myelin. The absence of MBP results in the loss of almost all compact myelin in the CNS. MBP mRNA is sorted into RNA granules that are transported to the periphery of oligodendrocytes in a translationally inactive state. A central mediator of this transport process is the trans-acting factor heterogeneous nuclear ribonucleoprotein (hnRNP) A2 that binds to the cis-acting A2-response element in the 3′UTR of MBP mRNA. Recently, we found that activation of the Src family nonreceptor tyrosine kinase Fyn in oligodendrocytes leads to phosphorylation of hnRNP A2 and to increased translation of MBP mRNA. Here, we identify…
Magnetic braking and damping of differential rotation in massive stars
2018
Fragmentation of highly differentially rotating massive stars that undergo collapse has been suggested as a possible channel for binary black hole formation. Such a scenario could explain the formation of the new population of massive black holes detected by the LIGO/VIRGO gravitational wave laser interferometers. We probe that scenario by performing general relativistic magnetohydrodynamic simulations of differentially rotating massive stars supported by thermal radiation pressure plus a gas pressure perturbation. The stars are initially threaded by a dynamically weak, poloidal magnetic field confined to the stellar interior. We find that magnetic braking and turbulent viscous damping via …
Implications for dark matter direct detection in the presence of LIGO-motivated primordial black holes
2019
We discuss formation of dark matter (DM) mini-halos around primordial black holes (PBHs) and its implication on DM direct detection experiments, including axion searches. Motivated by LIGO observations, we consider $f_{\textrm{DM}} \simeq 0.01$ as the fraction of DM in PBHs with masses $10 M_{\odot} - 70 M_{\odot}$. In this case, we expect the presence of dressed PBHs after Milky Way halo formation with mini-halo masses peaked around $M_{\textrm{halo}} \sim (50-55) M_{\textrm{PBH}}$. We analyze the effect of tidal forces acting on dressed PBHs within the Milky Way galaxy. In the solar neighborhood, the mini-halos are resistant against tidal disruption from the mean-field potential of the ga…
Constraints on Cosmic Strings Using Data from the Third Advanced LIGO–Virgo Observing Run
2021
We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 data set. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks and, for the first time, kink-kink collisions.cA template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension, $G\mu$, as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models.cAdditionally, we develop and test a third model which interpolat…
Cosmological waveguides for gravitational waves
1997
We study the linearized equations describing the propagation of gravitational waves through dust. In the leading order of the WKB approximation, dust behaves as a non-dispersive, non-dissipative medium. Taking advantage of these features, we explore the possibility that a gravitational wave from a distant source gets trapped by the gravitational field of a long filament of galaxies of the kind seen in the large scale structure of the Universe. Such a waveguiding effect may lead to a huge magnification of the radiation from distant sources, thus lowering the sensitivity required for a successful detection of gravitational waves by detectors like VIRGO, LIGO and LISA.