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Hemagglutinin Esterase
Hemagglutinin esterase (HEs) is a glycoprotein that certain enveloped viruses possess and use as an invading mechanism. HEs helps in the attachment and destruction of certain sialic acid receptors that are found on the host cell surface. Viruses that possess HEs include '' influenza C virus'', toroviruses, and coronaviruses of the subgenus '' Embecovirus'' (which does not include SARS-like coronaviruses). HEs is a dimer transmembrane protein consisting of two monomers, each monomer is made of three domains. The three domains are: membrane fusion, esterase, and receptor binding domains. The different HEs enzyme activities include: receptor binding activity, receptor hydrolysis ( esterase) activity, and membrane fusion activity. The receptor binding activity involve the attachment of HEs to N-acetyl-9-O-acetylneuraminic acid (9-O-Ac- Neu5Ac) of glycolipids and glycoproteins and in turn serve as viral receptor. Receptor hydrolysis (esterase) activity allows virus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycoprotein
Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. Secreted extracellular proteins are often glycosylated. In proteins that have segments extending extracellularly, the extracellular segments are also often glycosylated. Glycoproteins are also often important integral membrane proteins, where they play a role in cell–cell interactions. It is important to distinguish endoplasmic reticulum-based glycosylation of the secretory system from reversible cytosolic-nuclear glycosylation. Glycoproteins of the cytosol and nucleus can be modified through the reversible addition of a single GlcNAc residue that is considered reciprocal to phosphorylation and the functions of these are likely to be an additional regulatory mechanism that controls phosphorylation-based signalling. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Receptor Binding
In biochemistry and pharmacology, receptors are chemical structures, composed of protein, that receive and transduce signals that may be integrated into biological systems. These signals are typically chemical messengers which bind to a receptor and produce physiological responses, such as a change in the electrical activity of a cell. For example, GABA, an inhibitory neurotransmitter, inhibits electrical activity of neurons by binding to GABA receptors. There are three main ways the action of the receptor can be classified: relay of signal, amplification, or integration. Relaying sends the signal onward, amplification increases the effect of a single ligand, and integration allows the signal to be incorporated into another biochemical pathway. Receptor proteins can be classified by their location. Cell surface receptors, also known as transmembrane receptors, include ligand-gated ion channels, G protein-coupled receptors, and enzyme-linked hormone receptors. Intracellular rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Influenza A
''Influenza A virus'' (''Alphainfluenzavirus influenzae'') or IAV is the only species of the genus ''Alphainfluenzavirus'' of the virus family '' Orthomyxoviridae''. It is a pathogen with strains that infect birds and some mammals, as well as causing seasonal flu in humans. Mammals in which different strains of IAV circulate with sustained transmission are bats, pigs, horses and dogs; other mammals can occasionally become infected. IAV is an enveloped negative-sense RNA virus, with a segmented genome. Through a combination of mutation and genetic reassortment the virus can evolve to acquire new characteristics, enabling it to evade host immunity and occasionally to jump from one species of host to another. Subtypes of IAV are defined by the combination of the antigenic H and N proteins in the viral envelope; for example, "H1N1" designates an IAV subtype that has a type-1 hemagglutinin (H) protein and a type-1 neuraminidase (N) protein. Almost all possible combinations of H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Influenza C
Influenza C virus is the only species in the genus ''Gammainfluenzavirus'', in the virus family ''Orthomyxoviridae'', which like other influenza viruses, causes influenza. Influenza C viruses are known to infect humans and pigs. Flu due to the Type C species is rare compared with Types B or A, but can be severe and can cause local epidemics. Type C has 7 RNA segments and encodes 9 proteins, while Types A and B have 8 RNA segments and encode at least 10 proteins. Influenza C virus Influenza viruses are members of the family ''Orthomyxoviridae''. Influenza viruses A, B, C, and D represent the four antigenic types of influenza viruses. Of the four antigenic types, influenza A virus is the most severe, influenza B virus is less severe but can still cause outbreaks, and influenza C virus is usually only associated with minor symptoms. Influenza D virus is 50% similar in amino acid composition to influenza C virus, similar to the level of divergence between types A and B, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spike Protein
In virology, a spike protein or peplomer protein is a protein that forms a large structure known as a spike or peplomer projecting from the surface of an viral envelope, enveloped virus. as cited in The proteins are usually glycoproteins that form Protein dimer, dimers or Protein trimer, trimers. History and etymology The term "peplomer" refers to an individual spike from the viral surface; collectively the layer of material at the outer surface of the virion has been referred to as the "peplos". The term is derived from the Greek peplos, "a loose outer garment", "robe or cloak", or "woman['s] mantle". Early systems of viral taxonomy, such as the André Michel Lwoff, Lwoff–Robert Horne (virologist), Horne–Paul Tournier (virologist), Tournier system proposed in the 1960s, used the appearance and morphology of the "peplos" and peplomers as important characteristics for classification. More recently, the term "peplos" is considered a synonym for viral envelope. Properties S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuraminidase
Exo-α-sialidase (, sialidase, neuraminidase; systematic name acetylneuraminyl hydrolase) is a glycoside hydrolase that cleaves the glycosidic linkages of neuraminic acids: : Hydrolysis of α-(2→3)-, α-(2→6)-, α-(2→8)- glycosidic linkages of terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates Neuraminidase Enzyme, enzymes are a large family, found in a range of organisms. The best-known neuraminidase is the viral neuraminidase, a drug target for the prevention of the spread of influenza infection. Viral neuraminidase was the first neuraminidase to be identified. It was discovered in 1957 by Alfred Gottschalk (biochemist), Alfred Gottschalk at the WEHI, Walter and Eliza Hall Institute in Melbourne. The viral neuraminidases are frequently used as antigenic determinants found on the surface of the influenza virus. Some variants of the influenza neuraminidase confer more virulence to the virus than others. Ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemagglutinin
The term hemagglutinin (alternatively spelt ''haemagglutinin'', from the Greek , 'blood' + Latin , 'glue') refers to any protein that can cause red blood cells (erythrocytes) to clump together (" agglutinate") ''in vitro''. They do this by binding to the sugar residues on a red blood cell; when a single hemagglutinin molecule binds sugars from multiple red blood cells, it "glues" these cells together. As a result, they are carbohydrate-binding proteins (lectins). The ability to bind red blood cell sugars have independently appeared several times, and as a result hemaglutinins do not all bind using the same mechanism. The ability to bind red blood sugars is also not necessarily related to the ''in vivo'' function of the protein. The term ''hemagglutinin'' is most commonly applied to plant and viral lectins. Natural proteins that clump together red blood cells were known since the turn of the 19th century. Virologist George K. Hirst is also credited for "discovering agglutination a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Influenza Virus
''Orthomyxoviridae'' () is a family of negative-sense RNA viruses. It includes nine genera: '' Alphainfluenzavirus'', '' Betainfluenzavirus'', '' Gammainfluenzavirus'', '' Deltainfluenzavirus'', '' Isavirus'', '' Mykissvirus'', '' Quaranjavirus'', '' Sardinovirus'', and '' Thogotovirus''. The first four genera contain viruses that cause influenza in birds (see also avian influenza) and mammals, including humans. Isaviruses infect salmon; the thogotoviruses are arboviruses, infecting vertebrates and invertebrates (such as ticks and mosquitoes). The Quaranjaviruses are also arboviruses, infecting vertebrates (birds) and invertebrates (arthropods). The four genera of Influenza virus that infect vertebrates, which are identified by antigenic differences in their nucleoprotein and matrix protein, are as follows: * '' Alphainfluenzavirus'' infects humans, other mammals, and birds, and causes all flu pandemics * '' Betainfluenzavirus'' infects humans and seals * '' Gammainfluenz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of a cell, being selectively permeable to ions and organic mole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoplasm
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are the cytosol (a gel-like substance), the cell's internal sub-structures, and various cytoplasmic inclusions. In eukaryotes the cytoplasm also includes the nucleus, and other membrane-bound organelles.The cytoplasm is about 80% water and is usually colorless. The submicroscopic ground cell substance, or cytoplasmic matrix, that remains after the exclusion of the cell organelles and particles is groundplasm. It is the hyaloplasm of light microscopy, a highly complex, polyphasic system in which all resolvable cytoplasmic elements are suspended, including the larger organelles such as the ribosomes, mitochondria, plant plasti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genome
A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of junk DNA with no evident function. Almost all eukaryotes have mitochondrial DNA, mitochondria and a small mitochondrial genome. Algae and plants also contain chloroplast DNA, chloroplasts with a chloroplast genome. The study of the genome is called genomics. The genomes of many organisms have been Whole-genome sequencing, sequenced and various regions have been annotated. The first genome to be sequenced was that of the virus φX174 in 1977; the first genome sequence of a prokaryote (''Haemophilus influenzae'') was published in 1995; the yeast (''Saccharomyces cerevisiae'') genome was the first eukaryotic genome to be sequenced in 1996. The Human Genome Project ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetyl Group
In organic chemistry, an acetyl group is a functional group denoted by the chemical formula and the structure . It is sometimes represented by the symbol Ac (not to be confused with the element actinium). In IUPAC nomenclature, an acetyl group is called an ethanoyl group. An acetyl group contains a methyl group () that is single-bonded to a carbonyl (), making it an acyl group. The carbonyl center of an acyl radical has one non-bonded electron with which it forms a chemical bond to the remainder (denoted with the letter ''R'') of the molecule. The acetyl moiety is a component of many organic compounds, including acetic acid, the neurotransmitter acetylcholine, acetyl-CoA, acetylcysteine, acetaminophen (also known as paracetamol), and acetylsalicylic acid (also known as aspirin). Acetylation Acetylation is the chemical reaction known as "ethanoylation" in the IUPAC nomenclature. It depicts a reactionary process that injects an acetyl functional group into a chemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
