184,281 research outputs found
RECONSTITUTION OF ALLOPHYCOCYANIN FROM Mastigocladus laminosus WITH ISOLATED LINKER POLYPEPTIDE
No full textThe core linker polypeptide Lc 8.9 was isolated from Mastigocladus laminosus and purified on a preparative scale. A method for the reconstitution of allophycocyanin (AP)—linker complexes from isolated polypeptides was developed. The complex (αAP(βAP)3 Lc 8.9 was reconstituted and compared to (αAPβAP) and (αAPβAP)3 by sucrose density gradient ultracentrifugation, absorption, fluorescence emission and circular dichroism spectroscopy. Differences in the spectra of reconstituted and of directly isolated AP complexes are discussed
Fine mapping of posttranslational modifications of the linker histone H1 from Drosophila melanogaster.
No full textThe linker histone H1 binds to the DNA in between adjacent nucleosomes and contributes to chromatin organization and transcriptional control. It is known that H1 carries diverse posttranslational modifications (PTMs), including phosphorylation, lysine methylation and ADP-ribosylation. Their biological functions, however, remain largely unclear. This is in part due to the fact that most of the studies have been performed in organisms that have several H1 variants, which complicates the analyses. We have chosen Drosophila melanogaster, a model organism, which has a single H1 variant, to approach the study of the role of H1 PTMs during embryonic development. Mass spectrometry mapping of the entire sequence of the protein showed phosphorylation only in the ten N-terminal amino acids, mostly at S10. For the first time, changes in the PTMs of a linker H1 during the development of a multicellular organism are reported. The abundance of H1 monophosphorylated at S10 decreases as the embryos age, which suggests that this PTM is related to cell cycle progression and/or cell differentiation. Additionally, we have found a polymorphism in the protein sequence that can be mistaken with lysine methylation if the analysis is not rigorous
Cross-linker-Modulated Nanogel Flexibility Correlates with Tunable Targeting to a Sterically Impeded Endothelial Marker
No full textDeformability of
injectable nanocarriers impacts rheological behavior,
drug loading, and affinity target adhesion. Here, we present atomic
force microscopy (AFM) and spectroscopy measurements of nanocarrier
Young’s moduli, tune the moduli of deformable nanocarriers
with cross-linkers, and demonstrate vascular targeting behavior that
correlates with Young’s modulus. Homobifunctional cross-linkers
were introduced into lysozyme-dextran nanogels (NGs). Single particle-scale
AFM measurements determined NG moduli varying from ∼50–150
kPa for unmodified NGs or NGs with a short hydrophilic cross-linker
(2,2′-(ethylenedioxy)bis(ethylamine), EOD) to ∼350 kPa
for NGs modified with a longer hydrophilic cross-linker (4,9-dioxa-1,12-dodecanediamine,
DODD) to ∼10 MPa for NGs modified with a longer hydrophobic
cross-linker (1,12-diaminododecane, DAD). Cross-linked NGs were conjugated
to antibodies for plasmalemma vesicle associated protein (PLVAP),
a caveolar endothelial marker that cannot be accessed by rigid particles
larger than ∼100 nm. In previous work, 150 nm NGs effectively
targeted PLVAP, where rigid particles of similar diameter did not.
EOD-modified NGs targeted PLVAP less effectively than unmodified NGs,
but more effectively than DODD or DAD modified NGs, which both yielded
low levels of targeting, resembling results previously obtained with
polystyrene particles. Cross-linked NGs were also conjugated to antibodies
against intracellular adhesion molecule-1 (ICAM-1), an endothelial
marker accessible to large rigid particles. Cross-linked NGs and unmodified
NGs targeted uniformly to ICAM-1. We thus demonstrate cross-linker
modification of NGs, AFM determination of NG mechanical properties
varying with cross-linker, and tuning of specific sterically constrained
vascular targeting behavior in correlation with cross-linker-modified
NG mechanical properties
Cross-linker-Modulated Nanogel Flexibility Correlates with Tunable Targeting to a Sterically Impeded Endothelial Marker
No full textDeformability of
injectable nanocarriers impacts rheological behavior,
drug loading, and affinity target adhesion. Here, we present atomic
force microscopy (AFM) and spectroscopy measurements of nanocarrier
Young’s moduli, tune the moduli of deformable nanocarriers
with cross-linkers, and demonstrate vascular targeting behavior that
correlates with Young’s modulus. Homobifunctional cross-linkers
were introduced into lysozyme-dextran nanogels (NGs). Single particle-scale
AFM measurements determined NG moduli varying from ∼50–150
kPa for unmodified NGs or NGs with a short hydrophilic cross-linker
(2,2′-(ethylenedioxy)bis(ethylamine), EOD) to ∼350 kPa
for NGs modified with a longer hydrophilic cross-linker (4,9-dioxa-1,12-dodecanediamine,
DODD) to ∼10 MPa for NGs modified with a longer hydrophobic
cross-linker (1,12-diaminododecane, DAD). Cross-linked NGs were conjugated
to antibodies for plasmalemma vesicle associated protein (PLVAP),
a caveolar endothelial marker that cannot be accessed by rigid particles
larger than ∼100 nm. In previous work, 150 nm NGs effectively
targeted PLVAP, where rigid particles of similar diameter did not.
EOD-modified NGs targeted PLVAP less effectively than unmodified NGs,
but more effectively than DODD or DAD modified NGs, which both yielded
low levels of targeting, resembling results previously obtained with
polystyrene particles. Cross-linked NGs were also conjugated to antibodies
against intracellular adhesion molecule-1 (ICAM-1), an endothelial
marker accessible to large rigid particles. Cross-linked NGs and unmodified
NGs targeted uniformly to ICAM-1. We thus demonstrate cross-linker
modification of NGs, AFM determination of NG mechanical properties
varying with cross-linker, and tuning of specific sterically constrained
vascular targeting behavior in correlation with cross-linker-modified
NG mechanical properties
Cross-linker-Modulated Nanogel Flexibility Correlates with Tunable Targeting to a Sterically Impeded Endothelial Marker
No full textDeformability of
injectable nanocarriers impacts rheological behavior,
drug loading, and affinity target adhesion. Here, we present atomic
force microscopy (AFM) and spectroscopy measurements of nanocarrier
Young’s moduli, tune the moduli of deformable nanocarriers
with cross-linkers, and demonstrate vascular targeting behavior that
correlates with Young’s modulus. Homobifunctional cross-linkers
were introduced into lysozyme-dextran nanogels (NGs). Single particle-scale
AFM measurements determined NG moduli varying from ∼50–150
kPa for unmodified NGs or NGs with a short hydrophilic cross-linker
(2,2′-(ethylenedioxy)bis(ethylamine), EOD) to ∼350 kPa
for NGs modified with a longer hydrophilic cross-linker (4,9-dioxa-1,12-dodecanediamine,
DODD) to ∼10 MPa for NGs modified with a longer hydrophobic
cross-linker (1,12-diaminododecane, DAD). Cross-linked NGs were conjugated
to antibodies for plasmalemma vesicle associated protein (PLVAP),
a caveolar endothelial marker that cannot be accessed by rigid particles
larger than ∼100 nm. In previous work, 150 nm NGs effectively
targeted PLVAP, where rigid particles of similar diameter did not.
EOD-modified NGs targeted PLVAP less effectively than unmodified NGs,
but more effectively than DODD or DAD modified NGs, which both yielded
low levels of targeting, resembling results previously obtained with
polystyrene particles. Cross-linked NGs were also conjugated to antibodies
against intracellular adhesion molecule-1 (ICAM-1), an endothelial
marker accessible to large rigid particles. Cross-linked NGs and unmodified
NGs targeted uniformly to ICAM-1. We thus demonstrate cross-linker
modification of NGs, AFM determination of NG mechanical properties
varying with cross-linker, and tuning of specific sterically constrained
vascular targeting behavior in correlation with cross-linker-modified
NG mechanical properties
ATP-dependent chromatosome remodeling
No full textChromatin serves to package, protect and organize the complex eukaryotic genomes to assure their stable inheritance over many cell generations. At the same time, chromatin must be dynamic to allow continued use of DNA during a cell's lifetime. One important principle that endows chromatin with flexibility involves ATP-dependent `remodeling' factors, which alter DNA-histone interactions to form, disrupt or move nucleosomes. Remodeling is well documented at the nucleosomal level, but little is known about the action of remodeling factors in a more physiological chromatin environment. Recent findings suggest that some remodeling machines can reorganize even folded chromatin fibers containing the linker histone H1, extending the potential scope of remodeling reactions to the bulk of euchromatin
Linker Histone in Diseases
No full textThe linker histone is a protein that binds with the nucleosome, which is generally considered to achieve chromatin condensation in the nucleus. Accumulating evidences suggest that the linker histone is essential in the pathogenesis of several diseases. In this review, we briefly introduce the current knowledge of the linker histone, including its structure, characteristics and functions. Also, we move forward to present the advances of the linker histone's association with certain diseases, such as cancer, Alzheimer's disease, infection, male infertility and aberrant immunity situations, focusing on the alteration of the linker histone under certain pathological conditions and its role in developing each disease.National Natural Science Foundation of China [81672778, 81372165, 31261140372]; Beijing Natural Science Foundation [5142009]SCI(E)REVIEW81008-10181
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Individual Smad2 linker region phosphorylation sites determine the expression of proteoglycan and glycosaminoglycan synthesizing genes
No full textGrowth factors such as thrombin and transforming growth factor (TGF)-β facilitate glycosaminoglycan (GAG) chain hyperelongation on proteoglycans, a phenomenon that increases lipoprotein binding in the vessel wall and the development of atherosclerosis. TGF-β signals via canonical carboxy terminal phosphorylation of R-Smads and also non-canonical linker region phosphorylation of R-Smads. The G protein coupled receptor agonist, thrombin, can transactivate the TGF-β receptor leading to both canonical and non-canonical Smad signalling. Linker region phosphorylation drives the expression of genes for the synthesis of the proteoglycan, biglycan. Proteoglycan synthesis involves core protein synthesis, the initiation of GAG chains and the subsequent elongation of GAG chains. We have explored the relationship between the thrombin stimulated phosphorylation of individual serine and threonine sites in the linker region of Smad2 and the expression of GAG initiation xylosyltransferase-1 (XT-1) and GAG elongation chondroitin 4-sulfotransferase-1 (C4ST-1) and chondroitin synthase-1 (CHSY-1) genes. Thrombin stimulated the phosphorylation of all four target residues (Thr220, Ser245, Ser250 and Ser255 residues) with a similar temporal pattern – phosphorylation was maximal at 15 min (the earliest time point studied) and the level of the phospho-proteins declined thereafter over the following 4 h. Jnk, p38 and PI3K, selectively mediated the phosphorylation of the Thr220 residue whereas the serine residues were variously phosphorylated by multiple kinases. Thrombin stimulated the expression of all three genes – XT-1, C4ST-1 and CHSY-1. The three pathways mediating Thr220 phosphorylation were also involved in the expression of XT-1. The target pathways (excluding Jnk) were involved in the expression of the GAG elongation genes (C4ST-1 and CHSY-1). These findings support the contention that individual Smad linker region phosphorylation sites are linked to the expression of genes for the initiation and elongation of GAG chains on proteoglycans. The context of this work is that a specific inhibitor of GAG elongation represents a potential therapeutic agent for preventing GAG elongation and lipid binding and the results indicate that the specificity of the pathways is such that it might be therapeutically feasible to specifically target GAG elongation without interfering with other physiological processes with which proteoglycans are involved.Full Tex
The R domain and R-C linker are negative regulators of <i>V</i>. <i>vulnificus</i> LuxO ATPase activity.
No full text(A) Enzyme turnover number was measured using a coupled ATPase assay. Shown are LuxO-C, LuxO-RC (wild-type), and LuxO-RC phosphomimetic (R60E) and control (R60A) mutants. (B) The ATPase activity of LuxO-C (100 μM) was measured in the presence of increasing concentrations of LuxO-R+linker (residues 1–146) at three different ATP concentrations. Data are plotted as inhibition relative to LuxO-C only. (C) The ATPase activity of LuxO-C (100 μM) was measured in the presence of increasing concentrations of LuxO-R+linker, LuxO-R+linker (D60E), and LuxO-R (residues 1–128). ATP concentration was 0.5 mM. In all panels, error bars represent standard deviation (n = 3); where no error bar is visible, it is smaller than the corresponding symbol. The data underlying panels A–C can be found in S1 Data.</p
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