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HBX Hannover 14 (RaBoe)
HBx is a hepatitis B viral protein. It is 154 amino acids long and interferes with transcription, signal transduction, cell cycle progress, protein degradation, apoptosis and chromosomal stability in the host. It forms a heterodimeric complex with its cellular target protein (HBX interacting protein: HBXIP), and this interaction dysregulates centrosome dynamics and mitotic spindle formation. It interacts with DDB1 (Damaged DNA Binding Protein 1) redirecting the ubiquitin ligase activity of the CUL4-DDB1 E3 complexes, which are intimately involved in the intracellular regulation of DNA replication and repair, transcription and signal transduction. Although Protein X is normally absent in the Avihepadnavirus, a vestigial version has been identified in the duck hepatitis virus genome. Although it lacks significant sequence identity with any known vertebrate proteins, it seems likely that it evolved from a DNA glycosylase. Transgenic mice expressing the X protein in liver are m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HBV Genome , a former German trade union
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HBV may refer to: * Buskerud and Vestfold University College (Norwegian: ') * Hamengkubuwono V, 19th-century ruler of Yogyakarta, Java * ''Handbuch der Vögel Mitteleuropas'' (''Handbook of the Birds of Central Europe'') * HBV hydrology model * Hepatitis B virus * Hepatitis B vaccine * Heterostructure barrier varactor * Trade, Banking and Insurance Union The Trade, Banking and Insurance Union (german: Gewerkschaft Handel, Banken und Versicherungen, HBV) was a trade union representing workers in commerce and finance in Germany. During 1947 and 1948, German trade unionists were regrouping and the ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telomerase
Telomerase, also called terminal transferase, is a ribonucleoprotein that adds a species-dependent telomere repeat sequence to the 3' end of telomeres. A telomere is a region of repetitive sequences at each end of the chromosomes of most eukaryotes. Telomeres protect the end of the chromosome from DNA damage or from fusion with neighbouring chromosomes. The fruit fly ''Drosophila melanogaster'' lacks telomerase, but instead uses retrotransposons to maintain telomeres. Telomerase is a reverse transcriptase enzyme that carries its own RNA molecule (e.g., with the sequence 3′- CCC AA UCCC-5′ in ''Trypanosoma brucei'') which is used as a template when it elongates telomeres. Telomerase is active in gametes and most cancer cells, but is normally absent from, or at very low levels in, most somatic cells. History The existence of a compensatory mechanism for telomere shortening was first found by Soviet biologist Alexey Olovnikov in 1973, who also suggested the telomere hypothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Non-coding RNA
Long non-coding RNAs (long ncRNAs, lncRNA) are a type of RNA, generally defined as transcripts more than 200 nucleotides that are not translated into protein. This arbitrary limit distinguishes long ncRNAs from small non-coding RNAs, such as microRNAs (miRNAs), small interfering RNAs (siRNAs), Piwi-interacting RNAs (piRNAs), small nucleolar RNAs (snoRNAs), and other short RNAs. Long intervening/intergenic noncoding RNAs (lincRNAs) are sequences of lncRNA which do not overlap protein-coding genes. Long non-coding RNAs include intergenic lincRNAs, intronic ncRNAs, and sense and antisense lncRNAs, each type showing different genomic positions in relation to genes and exons. Abundance In 2007 a study found only one-fifth of transcription across the human genome is associated with protein-coding genes, indicating at least four times more long non-coding than coding RNA sequences. Large-scale complementary DNA (cDNA) sequencing projects such as FANTOM reveal the complexity of this t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MicroRNA
MicroRNA (miRNA) are small, single-stranded, non-coding RNA molecules containing 21 to 23 nucleotides. Found in plants, animals and some viruses, miRNAs are involved in RNA silencing and post-transcriptional regulation of gene expression. miRNAs base-pair to complementary sequences in mRNA molecules, then gene silence said mRNA molecules by one or more of the following processes: (1) cleavage of mRNA strand into two pieces, (2) destabilization of mRNA by shortening its poly(A) tail, or (3) translation of mRNA into proteins. This last method of gene silencing is the least efficient of the three, and requires the aid of ribosomes. miRNAs resemble the small interfering RNAs (siRNAs) of the RNA interference (RNAi) pathway, except miRNAs derive from regions of RNA transcripts that fold back on themselves to form short hairpins, whereas siRNAs derive from longer regions of double-stranded RNA. The human genome may encode over 1900 miRNAs, although more recent analysis suggests that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exon
An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts. In RNA splicing, introns are removed and exons are covalently joined to one another as part of generating the mature RNA. Just as the entire set of genes for a species constitutes the genome, the entire set of exons constitutes the exome. History The term ''exon'' derives from the expressed region and was coined by American biochemist Walter Gilbert in 1978: "The notion of the cistron… must be replaced by that of a transcription unit containing regions which will be lost from the mature messengerwhich I suggest we call introns (for intragenic regions)alternating with regions which will be expressedexons." This definition was originally made for protein-coding transcripts that are spliced before being translated. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regulation Of Transcription In Cancer
Generally, in progression to cancer, hundreds of genes are silenced or activated. Although silencing of some genes in cancers occurs by mutation, a large proportion of carcinogenic gene silencing is a result of altered DNA methylation (see DNA methylation in cancer). DNA methylation causing silencing in cancer typically occurs at multiple CpG sites in the CpG islands that are present in the promoters of protein coding genes. Altered expressions of microRNAs also silence or activate many genes in progression to cancer (see microRNAs in cancer). Altered microRNA expression occurs through hyper/hypo-methylation of CpG sites in CpG islands in promoters controlling transcription of the microRNAs. Silencing of DNA repair genes through methylation of CpG islands in their promoters appears to be especially important in progression to cancer (see methylation of DNA repair genes in cancer). CpG islands in promoters In humans, about 70% of promoters located near the transcription start ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer Epigenetics
Cancer epigenetics is the study of epigenetics, epigenetic modifications to the DNA of cancer cells that do not involve a change in the nucleotide sequence, but instead involve a change in the way the genetic code is expressed. Epigenetic mechanisms are necessary to maintain normal sequences of tissue specific gene expression and are crucial for normal development. They may be just as important, if not even more important, than mutation, genetic mutations in a cell's transformation to cancer. The disturbance of epigenetic processes in cancers, can lead to a loss of gene expression, expression of genes that occurs about 10 times more frequently by transcription silencing (caused by epigenetic promoter hypermethylation of CpG site#Methylation, silencing, cancer, and aging, CpG islands) than by mutations. As Vogelstein et al. points out, in a colorectal cancer there are usually about 3 to 6 driver mutations and 33 to 66 Genetic hitchhiking, hitchhiker or passenger mutations. However, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CpG Site
The CpG sites or CG sites are regions of DNA where a cytosine nucleotide is followed by a guanine nucleotide in the linear sequence of bases along its 5' → 3' direction. CpG sites occur with high frequency in genomic regions called CpG islands (or CG islands). Cytosines in CpG dinucleotides can be methylated to form 5-methylcytosines. Enzymes that add a methyl group are called DNA methyltransferases. In mammals, 70% to 80% of CpG cytosines are methylated. Methylating the cytosine within a gene can change its expression, a mechanism that is part of a larger field of science studying gene regulation that is called epigenetics. Methylated cytosines often mutate to thymines. In humans, about 70% of promoters located near the transcription start site of a gene (proximal promoters) contain a CpG island. CpG characteristics Definition ''CpG'' is shorthand for ''5'—C—phosphate—G—3' '', that is, cytosine and guanine separated by only one phosphate group; phosphate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Methylation
DNA methylation is a biological process by which methyl groups are added to the DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts to repress gene transcription. In mammals, DNA methylation is essential for normal development and is associated with a number of key processes including genomic imprinting, X-chromosome inactivation, repression of transposable elements, aging, and carcinogenesis. As of 2016, two nucleobases have been found on which natural, enzymatic DNA methylation takes place: adenine and cytosine. The modified bases are N6-methyladenineD. B. Dunn, J. D. Smith: ''The occurrence of 6-methylaminopurine in deoxyribonucleic acids.'' In: ''Biochem J.'' 68(4), Apr 1958, S. 627–636. PMID 13522672. ., 5-methylcytosineB. F. Vanyushin, S. G. Tkacheva, A. N. Belozersky: ''Rare bases in animal DNA.'' In: ''Nature.'' 225, 1970, S. 948–949. PMID 4391887. and N4- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endoplasmic Reticulum
The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum (RER), and smooth endoplasmic reticulum (SER). The endoplasmic reticulum is found in most eukaryotic cells and forms an interconnected network of flattened, membrane-enclosed sacs known as cisternae (in the RER), and tubular structures in the SER. The membranes of the ER are continuous with the outer nuclear membrane. The endoplasmic reticulum is not found in red blood cells, or spermatozoa. The two types of ER share many of the same proteins and engage in certain common activities such as the synthesis of certain lipids and cholesterol. Different types of cells contain different ratios of the two types of ER depending on the activities of the cell. RER is found mainly toward the nucleus of cell and SER towards the cell membrane or plasma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HBcAg
HBcAg (core antigen) is a hepatitis B viral protein. It is an indicator of active viral replication; this means the person infected with Hepatitis B can likely transmit the virus on to another person (i.e. the person is infectious). Structure and function HBcAg is an antigen that can be found on the surface of the nucleocapsid core (the inner most layer of the hepatitis B virus). While both HBcAg and HBeAg are made from the same open reading frame, HBcAg is not secreted. HBcAg is considered "particulate" and it does not circulate in the blood but recent study show it can be detected in serum by Radioimmunoassay. However, it is readily detected in hepatocytes after biopsy. The presence of both HBcAg and HBeAg proteins together act as a marker of viral replication, and antibodies to these antigens are a marker of declining replication. Interactions Tapasin can interact with HBcAg18-27 and enhance cytotoxic T-lymphocyte response against HBV. See also *HBeAg *HBsAg HBsAg (a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HBsAg
HBsAg (also known as the Australia antigen) is the surface antigen of the hepatitis B virus (HBV). Its presence in blood indicates current hepatitis B infection. Structure and function The viral envelope of an enveloped virus has different surface proteins from the rest of the virus which act as antigens. These antigens are recognized by antibody proteins that bind specifically to one of these surface proteins. Immunoassay Today, these antigen-proteins can be genetically manufactured (e.g. transgene '' E. coli'') to produce material for a simple antigen test, which detects the presence of HBV. It is present in the sera of patients with viral hepatitis B (with or without clinical symptoms). Patients who developed antibodies against HBsAg (anti-HBsAg seroconversion) are usually considered non-infectious. HBsAg detection by immunoassay is used in blood screening, to establish a diagnosis of hepatitis B infection in the clinical setting (in combination with other disease markers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
