Structural proteins linking the viral envelope with the virus core. They play a crucial role in virus assembly, and interact with the RNP complex as well as with the viral membrane. They are found in many enveloped viruses including paramyxoviruses, orthomyxoviruses, herpesviruses, retroviruses, filoviruses and other groups.
An example is the M1 protein of the influenza virus, showing affinity to the glycoproteins inserted in the host cell membrane on one side and affinity for the RNP complex molecules on the other side, which allows formation at the membrane of a complex made of the viral ribonucleoprotein at the inner side indirectly connected to the viral glycoproteins protruding from the membrane. This assembly complex will now bud out of the cell as new mature viruses.
Viral matrix proteins, like many other viral proteins, can exert different functions during the course of the infection. For example, in Rhabdoviruses, binding of M proteins to nucleocapsids is accountable for the formation of its “bullet” shaped virions.
In herpesviruses, the viral matrix is usually called viral tegument and contains many proteins involved in viral entry, early gene expression and immune evasion.
|Viral matrix protein|
Henipavirus is a genus of RNA viruses in the family Paramyxoviridae, order Mononegavirales containing five established species. Henipaviruses are naturally harboured by pteropid fruit bats (flying foxes) and microbats of several species. Henipaviruses are characterised by long genomes and a wide host range. Their recent emergence as zoonotic pathogens capable of causing illness and death in domestic animals and humans is a cause of concern.In 2009, RNA sequences of three novel viruses in phylogenetic relationship to known henipaviruses were detected in African straw-colored fruit bats (Eidolon helvum) in Ghana. The finding of these novel henipaviruses outside Australia and Asia indicates that the region of potential endemicity of henipaviruses may be worldwide. These African henipaviruses are slowly being characterised.KPNA3
Importin subunit alpha-3 is a protein that in humans is encoded by the KPNA3 gene.The transport of molecules between the nucleus and the cytoplasm in eukaryotic cells is mediated by the nuclear pore complex (NPC) which consists of 60–100 proteins and is probably 120 million daltons in molecular size. Small molecules (up to 70 kD) can pass through the nuclear pore by nonselective diffusion; larger molecules are transported by an active process. Most nuclear proteins contain short basic amino acid sequences known as nuclear localization signals (NLSs). KPNA3, encodes a protein similar to certain nuclear transport proteins of Xenopus and human. The predicted amino acid sequence shows similarity to Xenopus importin, yeast SRP1, and human RCH1 (KPNA2), respectively. The similarities among these proteins suggests that karyopherin alpha-3 may be involved in the nuclear transport system.KPNA4
Importin subunit alpha-4 is a protein that in humans is encoded by the KPNA4 gene.KPNA5
Importin subunit alpha-6 is a protein that in humans is encoded by the KPNA5 gene.The transport of molecules between the nucleus and the cytoplasm in eukaryotic cells is mediated by the nuclear pore complex (NPC) which consists of 60-100 proteins and is probably 120 million daltons in molecular size. Small molecules (up to 70 kD) can pass through the nuclear pore by nonselective diffusion; larger molecules are transported by an active process. Most nuclear proteins contain short basic amino acid sequences known as nuclear localization signals (NLSs). KPNA5 protein belongs to the importin alpha protein family and is thought to be involved in NLS-dependent protein import into the nucleusKPNA6
Importin subunit alpha-7 is a protein that in humans is encoded by the KPNA6 gene.Nucleocytoplasmic transport, a signal- and energy-dependent process, takes place through nuclear pore complexes embedded in the nuclear envelope. The import of proteins containing a nuclear localization signal (NLS) requires the NLS import receptor, a heterodimer of importin alpha and beta subunits also known as karyopherins. Importin alpha binds the NLS-containing cargo in the cytoplasm and importin beta docks the complex at the cytoplasmic side of the nuclear pore complex. In the presence of nucleoside triphosphates and the small GTP binding protein Ran, the complex moves into the nuclear pore complex and the importin subunits dissociate. Importin alpha enters the nucleoplasm with its passenger protein and importin beta remains at the pore. The protein encoded by this gene is a member of the importin alpha family.Karyopherin alpha 1
Importin subunit alpha-1 is a protein that in humans is encoded by the KPNA1 gene.Karyopherin alpha 2
Importin subunit alpha-2 is a protein that in humans is encoded by the KPNA2 gene.The import of proteins into the nucleus is a process that involves at least 2 steps. The first is an energy-independent docking of the protein to the nuclear envelope and the second is an energy-dependent translocation through the nuclear pore complex. Imported proteins require a nuclear localization sequence (NLS) which generally consists of a short region of basic amino acids or 2 such regions spaced about 10 amino acids apart. Proteins involved in the first step of nuclear import are members of the alpha importin family of karyopherins such as importin subunit alpha-2. These include the Xenopus protein importin and its yeast homolog, SRP1 (a suppressor of certain temperature-sensitive mutations of RNA polymerase I in Saccharomyces cerevisiae), which bind to the NLS. KPNA2 protein interacts with the NLSs of DNA helicase Q1 and SV40 T antigen and may be involved in the nuclear transport of proteins. KPNA2 also may play a role in V(D)J recombinationM protein
M protein may refer to:
M protein (Streptococcus), a virulence factor of the bacterium Streptococcus pyogenes
Another name for viral matrix protein, non structural protein linking the viral envelope with the virus capsid
Myeloma protein, also called paraprotein, an abnormal protein in the urine or blood, often seen in multiple myeloma or monoclonal gammopathy of undetermined significance
MYOM2 (Myomesin-2), a protein composing the M-line of muscle cell sarcomeres
Protein M in Mycoplasma genitalium which is different from the above-mentioned M proteinMyristoylation
Myristoylation is a lipidation modification where a myristoyl group, derived from myristic acid, is covalently attached by an amide bond to the alpha-amino group of an N-terminal glycine residue. Myristic acid is a 14-carbon saturated fatty acid (14:0) with the systematic name of n-Tetradecanoic acid. This modification can be added either co-translationally or post-translationally. N-myristoyltransferase (NMT) catalyzes the myristic acid addition reaction in the cytoplasm of cells. This lipidation event is the most found type of fatty acylation and is common among many organisms including animals, plants, fungi, protozoans and viruses. Myristoylation allows for weak protein–protein and protein–lipid interactions and plays an essential role in membrane targeting, protein–protein interactions and functions widely in a variety of signal transduction pathways.Strawberry crinkle virus
Strawberry crinkle virus (SCV) is a plant virus of the family Rhabdoviridae that infects plants of the genus Fragaria, commonly called "strawberries". It is transmitted by aphids of the genus Chaetosiphon. Virions are rod-shaped, enveloped, 74-88 nanometres (nm) in diameter and 163-383 nm in length, with surface projections. Its genome encodes at least five proteins including the nucleocapsid protein (45 kDa), the viral matrix protein (77 kDa), a nonstructural phosphoprotein (55 kDa), and a glycoprotein (23 kDa).VP40
In molecular biology, VP40 is the name of a Viral matrix protein. Most commonly it is found in the Ebola virus (EBOV), a type of non-segmented, negative-strand RNA virus. Ebola virus causes a severe and often fatal haemorrhagic fever in humans, known as Ebola virus disease. The virus matrix protein VP40 is a major structural protein that plays a central role in virus assembly and budding at the plasma membrane of infected cells. VP40 proteins work by associating with cellular membranes, interacting with the cytoplasmic tails of glycoproteins and binding to the ribonucleoprotein complex.