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Microprocessor Complex
The microprocessor complex is a protein complex involved in the early stages of processing microRNA (miRNA) and RNA interference (RNAi) in animal cells. The complex is minimally composed of the ribonuclease enzyme Drosha and the dimeric RNA-binding protein DGCR8 (also known as Pasha in non-human animals), and cleaves primary miRNA substrates to pre-miRNA in the cell nucleus. Microprocessor is also the smaller of the two multi-protein complexes that contain human Drosha. Composition The microprocessor complex consists minimally of two proteins: Drosha, a ribonuclease III enzyme; and DGCR8, a double-stranded RNA RNA-binding protein, binding protein. (DGCR8 is the name used in mammalian genetics, abbreviated from "DiGeorge syndrome critical region 8"; the homologous protein in model organisms such as Drosophila melanogaster, flies and Caenorhabditis elegans, worms is called ''Pasha'', for ''Pa''rtner of Dro''sha''.) The stoichiometry of the minimal complex was at one point expe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stoichiometry
Stoichiometry () is the relationships between the masses of reactants and Product (chemistry), products before, during, and following chemical reactions. Stoichiometry is based on the law of conservation of mass; the total mass of reactants must equal the total mass of products, so the relationship between reactants and products must form a ratio of positive integers. This means that if the amounts of the separate reactants are known, then the amount of the product can be calculated. Conversely, if one reactant has a known quantity and the quantity of the products can be empirically determined, then the amount of the other reactants can also be calculated. This is illustrated in the image here, where the unbalanced equation is: : : However, the current equation is imbalanced. The reactants have 4 hydrogen and 2 oxygen atoms, while the product has 2 hydrogen and 3 oxygen. To balance the hydrogen, a coefficient of 2 is added to the product H2O, and to fix the imbalance of oxygen, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (biology)
Transcription is the process of copying a segment of DNA into RNA for the purpose of gene expression. Some segments of DNA are transcribed into RNA molecules that can encode proteins, called messenger RNA (mRNA). Other segments of DNA are transcribed into RNA molecules called non-coding RNAs (ncRNAs). Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a Complementarity (molecular biology), complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, Antiparallel (biochemistry), antiparallel RNA strand called a primary transcript. In virology, the term transcription is used when referring to mRNA synthesis from a viral RNA molecule. The genome of many Orthornavirae, RNA viruses is composed of Sense (molecular biology), negative-sense RNA which acts as a template for positive sense viral messenger RNA - a necessary step in the synthesis of viral proteins needed for viral replication. This process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA Splicing
RNA splicing is a process in molecular biology where a newly-made precursor messenger RNA (pre-mRNA) transcription (biology), transcript is transformed into a mature messenger RNA (Messenger RNA, mRNA). It works by removing all the introns (non-coding regions of RNA) and ''splicing'' back together exons (coding regions). For nuclear genes, nuclear-encoded genes, splicing occurs in the cell nucleus, nucleus either during or immediately after Transcription (biology), transcription. For those eukaryotic transcription, eukaryotic genes that contain introns, splicing is usually needed to create an mRNA molecule that can be translation (biology), translated into protein. For many eukaryotic introns, splicing occurs in a series of reactions which are catalyzed by the spliceosome, a complex of small nuclear ribonucleoproteins (snRNPs). There exist self-splicing introns, that is, ribozymes that can catalyze their own excision from their parent RNA molecule. The process of transcription, spli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spliceosome
A spliceosome is a large ribonucleoprotein (RNP) complex found primarily within the nucleus of eukaryotic cells. The spliceosome is assembled from small nuclear RNAs ( snRNA) and numerous proteins. Small nuclear RNA (snRNA) molecules bind to specific proteins to form a small nuclear ribonucleoprotein complex (snRNP, pronounced "snurps"), which in turn combines with other snRNPs to form a large ribonucleoprotein complex called a spliceosome. The spliceosome removes introns from a transcribed pre-mRNA, a type of primary transcript. This process is generally referred to as splicing. An analogy is a film editor, who selectively cuts out irrelevant or incorrect material (equivalent to the introns) from the initial film and sends the cleaned-up version to the director for the final cut. However, sometimes the RNA within the intron acts as a ribozyme, splicing itself without the use of a spliceosome or protein enzymes. History In 1977, work by the Sharp and Roberts labs reve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intron
An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. The word ''intron'' is derived from the term ''intragenic region'', i.e., a region inside a gene."The notion of the cistron .e., gene... must be replaced by that of a transcription unit containing regions which will be lost from the mature messenger – which I suggest we call introns (for intragenic regions) – alternating with regions which will be expressed – exons." (Gilbert 1978) The term ''intron'' refers to both the DNA sequence within a gene and the corresponding RNA sequence in RNA transcripts. The non-intron sequences that become joined by this RNA processing to form the mature RNA are called exons. Introns are found in the genes of most eukaryotes and many eukaryotic viruses, and they can be located in both protein-coding genes and genes that function as RNA ( noncoding genes). There are four main types of introns: tRNA introns, group I introns, group I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not Translation (genetics), translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally important list of RNAs, types of non-coding RNAs include transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), as well as small RNAs such as microRNAs, siRNAs, piRNAs, snoRNAs, snRNAs, Extracellular RNA, exRNAs, scaRNAs and the long noncoding RNA, long ncRNAs such as Xist and HOTAIR. The number of non-coding RNAs within the human genome is unknown; however, recent Transcriptomics, transcriptomic and Bioinformatics, bioinformatic studies suggest that there are thousands of non-coding transcripts. Many of the newly identified ncRNAs have unknown functions, if any. There is no consensus on how much of non-coding transcription is functional: some believe most ncRNAs to be non-functional "junk RNA", spurious transcriptions, while others expect that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substrate (chemistry)
In chemistry, the term substrate is highly context-dependent. Broadly speaking, it can refer either to a chemical species being observed in a chemical reaction, or to a surface on which other chemical reactions or microscopy are performed. In the former sense, a reagent is added to the ''substrate'' to generate a product through a chemical reaction. The term is used in a similar sense in synthetic and organic chemistry, where the substrate is the chemical of interest that is being modified. In biochemistry, an enzyme substrate is the material upon which an enzyme acts. When referring to Le Chatelier's principle, the substrate is the reagent whose concentration is changed. ;Spontaneous reaction : :*Where S is substrate and P is product. ;Catalysed reaction : :*Where S is substrate, P is product and C is catalyst. In the latter sense, it may refer to a surface on which other chemical reactions are performed or play a supporting role in a variety of spectroscopic and micr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem-loop
Stem-loops are nucleic acid Biomolecular structure, secondary structural elements which form via intramolecular base pairing in single-stranded DNA or RNA. They are also referred to as hairpins or hairpin loops. A stem-loop occurs when two regions of the same nucleic acid strand, usually Complementarity (molecular biology), complementary in nucleotide sequence, base-pair to form a double helix that ends in a loop of unpaired nucleotides. Stem-loops are most commonly found in RNA, and are a key building block of many RNA biomolecular structure#Secondary structure, secondary structures. Stem-loops can direct RNA folding, protect structural stability for messenger RNA (mRNA), provide recognition sites for RNA-binding protein, RNA binding proteins, and serve as a Substrate (chemistry), substrate for Enzyme catalysis, enzymatic reactions. Formation and stability The formation of a stem-loop is dependent on the stability of the helix and loop regions. The first prerequisite is the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precursor MRNA
Precursor or Precursors may refer to: *Precursor (religion), a forerunner, predecessor ** The Precursor, John the Baptist Science and technology * Precursor (bird), hypothesized genus of fossil birds that was composed of fossilized parts of unrelated animals * Precursor (chemistry), compound that participates in the chemical reaction that produces another compound * Precursor (physics), phenomenon of wave patterns caused by the dispersion of an impulse's frequency components as it propagates through a medium * Precursor in the Course (medicine), course of a disease, the state preceding a particular stage in that course * Precursor cell (biology), a unipotent stem cell * Earthquake precursor, phenomenon that occurs before an earthquake and allegedly -though, so far, not demonstrably- can predict the earthquake * Gehrlein Precursor, a glider * LNWR Precursor Class (other), classes of passenger locomotives developed for the London and North Western Railway Fiction *Elder rac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary MiRNA
Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ''Primary'' (album) by Rubicon (2002) * "Primary" (song) by The Cure * "Primary", song by Spoon from the album ''Telephono'' Other uses in arts, entertainment, and media * Primaries or primary beams, in E. E. Smith's science-fiction series ''Lensman'' * ''Primary'' (film), American political documentary (1960) Computing * PRIMARY, an X Window selection * Primary data storage, computer technology used to retain digital data * Primary server, main server on the server farm Education * Primary education, the first stage of compulsory education * Primary FRCA, academic examination for anaesthetists in the U.K. * Primary school, school providing primary education Mathematics * ''p''-group of prime power order * Primary decomposition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
