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Adenovirus E1B Protein
Adenovirus E1B protein usually refers to one of two proteins transcribed from the E1B gene of the adenovirus: a 55kDa protein and a 19kDa protein. These two proteins are needed to block apoptosis in adenovirus-infected cells. E1B proteins work to prevent apoptosis that is induced by the small adenovirus E1A protein, which stabilizes p53, a tumor suppressor. Functions E1B-19k E1B-19k blocks a p53-independent apoptosis mechanism. Without E1B-19k, degradation of both cellular and viral DNA occurs, in addition to premature host cell death during the lytic cycle, thus limiting viral replication. E1B-19k mimics MCL1, which is a cellular antiapoptotic protein. In infected cells, the expression of E1A results in the degradation of MCL-1, which normally binds the propaptotic protein, BAK. BAK activation induces apoptosis by cooligomerizing with another proapoptotic protein, BAX. Together, BAK and BAX form pores in the mitochondrial membrane, releasing apoptogenic proteins like cytochrome c. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteins
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (genetics)
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called non-coding RNAs (ncRNAs). mRNA comprises only 1–3% of total RNA samples. Less than 2% of the human genome can be transcribed into mRNA ( Human genome#Coding vs. noncoding DNA), while at least 80% of mammalian genomic DNA can be actively transcribed (in one or more types of cells), with the majority of this 80% considered to be ncRNA. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. Transcription proceeds in the following general steps: # RNA polymerase, together with one or more general transcription factors, binds to promoter DNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenovirus
Adenoviruses (members of the family ''Adenoviridae'') are medium-sized (90–100 nm), nonenveloped (without an outer lipid bilayer) viruses with an icosahedral nucleocapsid containing a double-stranded DNA genome. Their name derives from their initial isolation from human adenoids in 1953. They have a broad range of vertebrate hosts; in humans, more than 50 distinct adenoviral serotypes have been found to cause a wide range of illnesses, from mild respiratory infections in young children (known as the common cold) to life-threatening multi-organ disease in people with a weakened immune system. Virology Classification This family contains the following genera: * '' Atadenovirus'' * '' Aviadenovirus'' * '' Ichtadenovirus'' * '' Mastadenovirus'' (including all human adenoviruses) * '' Siadenovirus'' * '' Testadenovirus'' Diversity In humans, currently there are 88 human adenoviruses (HAdVs) in seven species (Human adenovirus A to G): * A: 12, 18, 31 * B: 3, 7, 11, 14, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MCL1
Induced myeloid leukemia cell differentiation protein Mcl-1 is a protein that in humans is encoded by the ''MCL1'' gene. Function The protein encoded by this gene belongs to the Bcl-2 family. Alternative splicing occurs at this locus and two transcript variants encoding distinct isoforms have been identified. The longer gene product (isoform 1) enhances cell survival by inhibiting apoptosis while the alternatively spliced shorter gene product (isoform 2) promotes apoptosis and is death-inducing. The protein MCL1 has a very short biological half-life of only 20–30 minutes. The loss of MCL1 has a more dramatic impact than the loss of any other anti-apoptotic member of the Bcl-2 family. Loss of the ''Mcl-1'' gene results in embryo death when the embryo is only around 3.5 days old, before it has even implanted. Conditional deletion of ''Mcl-1'' depletes a wide variety of cells, including hematopoietic stem cells, B cell–committed progenitors, T cell–committed progenitors, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytochrome C
The cytochrome complex, or cyt ''c'', is a small hemeprotein found loosely associated with the inner membrane of the mitochondrion. It belongs to the cytochrome c family of proteins and plays a major role in cell apoptosis. Cytochrome c is highly water-soluble, unlike other cytochromes, and is an essential component of the respiratory electron transport chain, where it carries one electron. It is capable of undergoing oxidation and reduction as its iron atom converts between the ferrous and ferric forms, but does not bind oxygen. It transfers electrons between Complexes III (Coenzyme Q – Cyt c reductase) and IV (Cyt c oxidase). In humans, cytochrome c is encoded by the ''CYCS'' gene. Species distribution Cytochrome c is a highly conserved protein across the spectrum of eukaryotic species, found in plants, animals, fungi, and many unicellular organisms. This, along with its small size (molecular weight about 12,000 daltons), makes it useful in studies of cladistics. Cyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caspase-9
Caspase-9 is an enzyme that in humans is encoded by the CASP9 gene. It is an initiator caspase, critical to the apoptotic pathway found in many tissues. Caspase-9 homologs have been identified in all mammals for which they are known to exist, such as ''Mus musculus'' and ''Pan troglodytes''. Caspase-9 belongs to a family of caspases, cysteine-aspartic proteases involved in apoptosis and cytokine signalling. Apoptotic signals cause the release of cytochrome c from mitochondria and activation of apaf-1 (apoptosome), which then cleaves the pro-enzyme of caspase-9 into the active dimer form. Regulation of this enzyme occurs through phosphorylation by an allosteric inhibitor, inhibiting dimerization and inducing a conformational change. Correct caspase-9 function is required for apoptosis, leading to the normal development of the central nervous system. Caspase-9 has multiple additional cellular functions that are independent of its role in apoptosis. Nonapoptotic roles of caspase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caspase-3
Caspase-3 is a caspase protein that interacts with caspase-8 and caspase-9. It is encoded by the ''CASP3'' gene. ''CASP3'' orthologs have been identified in numerous mammals for which complete genome data are available. Unique orthologs are also present in birds, lizards, lissamphibians, and teleosts. The CASP3 protein is a member of the cysteine-aspartic acid protease (caspase) family. Sequential activation of caspases plays a central role in the execution-phase of cell apoptosis. Caspases exist as inactive proenzymes that undergo proteolytic processing at conserved aspartic residues to produce two subunits, large and small, that dimerize to form the active enzyme. This protein cleaves and activates caspases 6 and 7; and the protein itself is processed and activated by caspases 8, 9, and 10. It is the predominant caspase involved in the cleavage of amyloid-beta 4A precursor protein, which is associated with neuronal death in Alzheimer's disease. Alternative splicing of this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MRN Complex
The MRN complex (MRX complex in yeast) is a protein complex consisting of Mre11, Rad50 and Nbs1 (also known as Nibrin in humans and as Xrs2 in yeast). In eukaryotes, the MRN/X complex plays an important role in the initial processing of double-strand DNA breaks prior to repair by homologous recombination or non-homologous end joining. The MRN complex binds avidly to double-strand breaks both in vitro and in vivo and may serve to tether broken ends prior to repair by non-homologous end joining or to initiate DNA end resection prior to repair by homologous recombination. The MRN complex also participates in activating the checkpoint kinase ATM in response to DNA damage. Production of short single-strand oligonucleotides by Mre11 endonuclease activity has been implicated in ATM activation by the MRN complex. Evolutionary ancestry and biologic function The MRN complex has been mainly studied in eukaryotes. However, recent work shows that two of the three protein components of this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mastadenovirus
''Mastadenovirus'' is a genus of viruses in the family ''Adenoviridae''. Humans and other mammals serve as natural hosts. There are 51 species in this genus. The genus as a whole includes many very common causes of human infection, estimated to be responsible for 2 to 5% of all respiratory infections, as well as gastrointestinal and eye infections. Symptoms are usually mild. Specific tropisms include: serotypes 3, 5, and 7: lower respiratory tract infections, serotypes 8, 19, and 37: epidemic keratoconjunctivitis, serotypes 4 and 7: acute respiratory disease, serotypes 40 and 41: gastroenteritis, serotype 14: can cause potentially fatal adenovirus infections. Canine mastadenovirus A (formerly canine adenovirus-1, CAdV-1) can lead to death in puppies, or encephalitis in other carnivore species. Etymology The name ''Mastadenovirus'' is derived from the Greek word ''mastos'' 'breast' (hence ''mammal'') and ''adenovirus'', named for the human adenoids, which the virus was first i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exaptation
Exaptation and the related term co-option describe a shift in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and behaviour. Bird feathers are a classic example. Initially they may have evolved for temperature regulation, but later were adapted for flight. When feathers were first used to aid in flight, that was an exaptive use. They have since then been shaped by natural selection to improve flight, so in their current state they are best regarded as adaptations for flight. So it is with many structures that initially took on a function as an exaptation: once molded for a new function, they become further adapted for that function. Interest in exaptation relates to both the process and products of evolution: the process that creates complex traits and the products (functions, anatomical structures, biochemicals, etc.) that may b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atadenovirus
''Atadenovirus'' is a genus of viruses, in the family ''Adenoviridae Adenoviruses (members of the family ''Adenoviridae'') are medium-sized (90–100 nm), nonenveloped (without an outer lipid bilayer) viruses with an icosahedral nucleocapsid containing a double-stranded DNA genome. Their name derives from the ...''. Vertebrates serve as natural hosts. There are 10 species in this genus. Taxonomy The genus contains the following 10 species: * '' Bovine atadenovirus D'' * '' Bovine atadenovirus E'' * '' Deer atadenovirus A'' * '' Duck atadenovirus A'' * '' Lizard atadenovirus A'' * '' Lizard atadenovirus B'' * '' Ovine atadenovirus D'' * '' Possum atadenovirus A'' * '' Psittacine atadenovirus A'' * '' Snake atadenovirus A'' Structure Viruses in ''Atadenovirus'' are non-enveloped, with icosahedral geometries, and T=25 symmetry. The diameter is around 90 nm. Genomes are linear and non-segmented, around 30kb in length. The genome codes for 30 proteins. Life cycle Vira ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oncolytic Adenovirus
Adenovirus varieties have been explored extensively as a viral vector for gene therapy and also as an oncolytic virus. Of the many different viruses being explored for oncolytic potential, an adenovirus was the first to be approved by a regulatory agency, the genetically modified H101 strain. It gained regulatory approval in 2005 from China's State Food and Drug Administration (SFDA) for the treatment of head and neck cancer. Engineering of oncolytic adenovirus Adenoviruses have so far been through three generations of development. Some of the strategies for modification of adenoviruses are described below. Attenuation For adenovirus replication to occur, the host cell must be induced into S phase by viral proteins interfering with cell cycle proteins. The adenoviral E1A gene is responsible for inactivation of several proteins, including retinoblastoma, allowing entry into S-phase. The adenovirus E1B55kDa gene cooperates with another adenoviral product, E4ORF6, to inactivate p5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
