The interaction of a series of hybridoma IgGs with reovirus particles Demonstration that the core protein λ2 is exposed on the particle surface

Virology ◽  
1981 ◽  
Vol 108 (1) ◽  
pp. 147-155 ◽  
Author(s):  
Edward C. Hayes ◽  
Patrick W.K. Lee ◽  
Sara E. Miller ◽  
Wolfgang K. Joklik
Keyword(s):  
Core Protein ◽  
Particle Surface ◽  
The Core

Analysis of small nuclear ribonucleoproteins (RNPs) in Trypanosoma brucei: structural organization and protein components of the spliced leader RNP

1991 ◽  
Vol 11 (11) ◽  
pp. 5516-5526 ◽  
Author(s):  
M Cross ◽  
A Günzl ◽  
Z Palfi ◽  
A Bindereif
Keyword(s):  
Trypanosoma Brucei ◽  
Core Protein ◽  
Rnase H ◽  
Spliced Leader ◽  
The Core ◽  
In Vitro Reconstitution ◽  
U2 Snrnp ◽  
Protein Components ◽  
Small Nuclear Ribonucleoproteins

trans splicing in Trypanosoma brucei involves the ligation of the 40-nucleotide spliced leader (SL) to each of the exons of large, polycistronic pre-mRNAs and requires the function of small nuclear ribonucleoproteins (snRNPs). We have identified and characterized snRNP complexes of SL, U2, U4, and U6 RNAs in T. brucei extracts by a combination of glycerol gradient sedimentation, CsCl density centrifugation, and anti-m3G immunoprecipitation. Both the SL RNP and the U4/U6 snRNP contain salt-stable cores; the U2 snRNP, in contrast to other eucaryotic snRNPs, is not stable under stringent ionic conditions. Two distinct complexes of U6 RNA were found, a U6 snRNP and a U4/U6 snRNP. The structure of the SL RNP was analyzed in detail by oligonucleotide-directed RNase H protection and by in vitro reconstitution. Our results indicate that the 3' half of SL RNA constitutes the core protein-binding domain and that protein components of the SL RNP also bind to the U2 and U4 RNAs. Using antisense RNA affinity chromatography, we identified a set of low-molecular-mass proteins (14.8, 14, 12.5, and 10 kDa) as components of the core SL RNP.

scholarly journals Reciprocal action of Casein Kinase Iε on core planar polarity proteins regulates clustering and asymmetric localisation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Helen Strutt ◽  
Jessica Gamage ◽  
David Strutt
Keyword(s):  
Core Protein ◽  
Intercellular Junctions ◽  
Casein Kinase ◽  
Planar Polarity ◽  
The Core ◽  
Pupal Wing ◽  
Polarity Proteins ◽  
Conserved Core

The conserved core planar polarity pathway is essential for coordinating polarised cell behaviours and the formation of polarised structures such as cilia and hairs. Core planar polarity proteins localise asymmetrically to opposite cell ends and form intercellular complexes that link the polarity of neighbouring cells. This asymmetric segregation is regulated by phosphorylation through poorly understood mechanisms. We show that loss of phosphorylation of the core protein Strabismus in the Drosophila pupal wing increases its stability and promotes its clustering at intercellular junctions, and that Prickle negatively regulates Strabismus phosphorylation. Additionally, loss of phosphorylation of Dishevelled – which normally localises to opposite cell edges to Strabismus – reduces its stability at junctions. Moreover, both phosphorylation events are independently mediated by Casein Kinase Iε. We conclude that Casein Kinase Iε phosphorylation acts as a switch, promoting Strabismus mobility and Dishevelled immobility, thus enhancing sorting of these proteins to opposite cell edges.

scholarly journals Hepatitis B viral core proteins with an N-terminal extension can assemble into core-like particles but cannot be enveloped

1999 ◽  
Vol 80 (10) ◽  
pp. 2647-2659 ◽  
Author(s):  
Eric Ka-Wai Hui ◽  
Yong Shyang Yi ◽  
Szecheng J. Lo
Keyword(s):  
Hepatitis B ◽  
Kinase Activity ◽  
Core Protein ◽  
Surface Antigens ◽  
Human Hepatoma Cells ◽  
The Core ◽  
Core Proteins ◽  
B Virus ◽  
Transfection Medium ◽  
Cscl Gradient

The structure of hepatitis B virus (HBV) nucleocapsids has been revealed in great detail by cryoelectron microscopy. How nucleocapsids interact with surface antigens to form enveloped virions remains unknown. In this study, core mutants with N-terminal additions were created to address two questions: (1) can these mutant core proteins still form nucleocapsids and (2) if so, can the mutant nucleocapsids interact with surface antigens to form virion-like particles. One plasmid encoding an extra stretch of 23 aa, including six histidine residues, fused to the N terminus of the core protein (designated HisC183) was expressed in Escherichia coli and detected by Western blot. CsCl gradient and electron microscopy analyses indicated that HisC183 could self-assemble into nucleocapsids. When HisC183 or another similar N-terminal fusion core protein (designated FlagC183) was co-expressed with a core-negative plasmid in human hepatoma cells, both mutant core proteins self-assembled into nucleocapsids. These particles also retained kinase activity. Using an endogenous polymerase assay, a fill-in HBV DNA labelled with isotope was obtained from intracellular nucleocapsids formed by mutant cores. In contrast, no such signal was detected from the transfection medium, which was consistent with PCR and Southern blot analyses. Results indicate that core mutants with N-terminal extensions can form nucleocapsids, but are blocked during the envelopment process and cannot form secreted virions. The mutant nucleocapsids generated from this work should facilitate further study on how nucleocapsids interact with surface antigens.

scholarly journals Modulation of aggrecan and link-protein synthesis in articular cartilage

1992 ◽  
Vol 288 (3) ◽  
pp. 721-726 ◽  
Author(s):  
A J Curtis ◽  
R J Devenish ◽  
C J Handley
Keyword(s):  
Articular Cartilage ◽  
Half Life ◽  
Core Protein ◽  
Calf Serum ◽  
Cartilage Explants ◽  
Dependent Manner ◽  
Link Protein ◽  
The Core ◽  
Explant Cultures ◽  
Igf I

The addition of serum or insulin-like growth factor-I (IGF-I) to the medium of explant cultures of bovine articular cartilage is known to stimulate the synthesis of aggrecan in a dose-dependent manner. The half-life of the pool of proteoglycan core protein was measured in adult articular cartilage cultured for 6 days in the presence and absence of 20 ng of IGF-I/ml and shown to be 24 min under both sets of conditions. The half-life of the mRNA pool coding for aggrecan was also determined and shown to be approx. 4 h in cartilage maintained in culture with or without IGF-I. The pool size of mRNA coding for aggrecan core protein increased 5-6-fold in cartilage explants maintained in culture in medium containing 20% (v/v) fetal-calf serum; however, in tissue maintained with medium containing IGF-I there was no increase in the cellular levels of this mRNA. This suggests that aggrecan synthesis is stimulated by IGF-I at the level of translation of mRNA coding for the core protein of this proteoglycan and that other growth factors are present in serum that stimulate aggrecan synthesis at the level of transcription of the core-protein gene. Inclusion of serum or IGF-I in the medium of cartilage explant cultures induced increases in the amounts of mRNA coding for type II collagen and link protein, whereas only serum enhanced the amount of mRNA for the core protein of decorin.

scholarly journals Induction of HOX genes by HCV infection via impairment of histone H2A monoubiquitination.

2020 ◽  
pp. JVI.01784-20
Author(s):  
Hirotake Kasai ◽  
Kazuki Mochizuki ◽  
Tomohisa Tanaka ◽  
Atsuya Yamashita ◽  
Yoshiharu Matsuura ◽  
...  
Keyword(s):  
Hepatitis C ◽  
Protein Expression ◽  
Hox Genes ◽  
Core Protein ◽  
Gene Promoter ◽  
Hcv Infection ◽  
Histone H2a ◽  
Hox Gene ◽  
The Core ◽  
Hcv Core Protein

Hepatitis C virus (HCV) infection causes liver pathologies, including hepatocellular carcinoma (HCC). Homeobox (HOX) gene products regulate embryonic development and are associated with tumorigenesis, although the regulation of HOX genes by HCV infection has not been clarified in detail. We examined the effect of HCV infection on HOX gene expression. In this study, HCV infection induced more than half of the HOX genes and reduced the level of histone H2A monoubiquitination on lysine (K) 119 (H2Aub), which represses HOX gene promoter activity. HCV infection also promoted proteasome-dependent degradation of RNF2, which is an E3 ligase mediating H2A monoubiquitination as a component of polycomb repressive complex 1. Since full-genomic replicon cells but not subgenomic replicon cells exhibited reduced RNF2 and H2Aub levels and induction of HOX genes, we focused on the core protein. Expression of the core protein reduced the amounts of RNF2 and H2Aub and induced HOX genes. Treatment with LY-411575, which can reduce HCV core protein expression via SPP inhibition without affecting other viral proteins, dose-dependently restored the amounts of RNF2 and H2Aub in HCV-infected cells and impaired the induction of HOX genes and production of viral particles but not viral replication. The chromatin immunoprecipitation assay results also indicated infection- and proteasome-dependent reductions in H2Aub located in HOX gene promoters. These results suggest that HCV infection or core protein induces HOX genes by impairing histone H2A monoubiquitination via a reduction in the RNF2 level.Importance Recently sustained virologic response can be achieved by direct acting antiviral therapy in most of hepatitis C patients. Unfortunately, DAA therapy does not completely eliminate a risk of HCC. Several epigenetic factors, including histone modifications, are well known to contribute to HCV-associated HCC. However, the regulation of histone modifications by HCV infection has not been clarified in detail. In this study, our data suggest that HCV infection or HCV core protein expression impairs monoubiquitination of histone H2A K119 in HOX gene promoter via destabilization of RNF2 and then induces HOX genes. Several lines of evidence suggest that the expression of several HOX genes is dysregulated in certain types of tumors. These findings reveal a novel mechanism of HCV-related histone modification and may provide information about new targets for diagnosis and prevention of HCC occurrence.

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