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Capping Enzyme
A capping enzyme (CE) is an enzyme that catalyzes the attachment of the 5' cap to messenger RNA molecules that are in the process of being synthesized in the cell nucleus during the first stages of gene expression. The addition of the cap occurs co-transcriptionally, after the growing RNA molecule contains as little as 25 nucleotides. The enzymatic reaction is catalyzed specifically by the phosphorylated carboxyl-terminal domain (CTD) of RNA polymerase II. The 5' cap is therefore specific to RNAs synthesized by this polymerase rather than those synthesized by RNA polymerase I or RNA polymerase III. Pre-mRNA undergoes a series of modifications - 5' capping, splicing and 3' polyadenylation before becoming mature mRNA that exits the nucleus to be translated into functional proteins and capping of the 5' end is the first of these modifications. Three enzymes, RNA triphosphatase, guanylyltransferase (or CE), and methyltransferase are involved in the addition of the methylated 5' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDB 1ckm EBI
PDB or pdb may refer to: Organizations * Party of German-speaking Belgians (German: '), a former Belgian political party * Promised Day Brigade, a former Iraqi organization Science and technology * Protein Data Bank, a biological molecule database ** Protein Data Bank (file format) * Potato dextrose broth, a microbiological growth medium * Pee Dee Belemnite, a reference standard for isotopes; see δ13C#Reference standard, ''δ''13C Computing * PDB (Palm OS), a record database format * Pluggable database, in Oracle Database * Program database, a debugging information format * Python Debugger (pdb), of the Python programming language; see Stepping (debugging)#Techniques for program animation, Stepping Other uses * Chess Problem Database Server (PDB Server), a repository for chess problems * Pousette-Dart Band, an American band * President's Daily Brief, a US intelligence document See also * 1,4-Dichlorobenzene or ''para''-dichlorobenzene (PDCB), a chemical [Baidu] |
Guanylyltransferase
Guanylyl transferases are enzymes that transfer a guanosine mono phosphate group, usually from GTP to another molecule, releasing pyrophosphate. Many eukaryotic guanylyl transferases are capping enzymes that catalyze the formation of the 5' cap in the co-transcriptional modification of messenger RNA. Because the 5' end of the RNA molecule ends in a phosphate group, the bond formed between the RNA and the GTP molecule is an unusual 5'-5' triphosphate linkage, instead of the 3'-5' linkages between the other nucleotides that form an RNA strand. In capping enzymes, a highly conserved lysine residue serves as the catalytic residue that forms a covalent enzyme-GMP complex.Fresco LD, Buratowski S. (1994). Active site of the mRNA-capping enzyme guanylyltransferase from Saccharomyces cerevisiae: similarity to the nucleotidyl attachment motif of DNA and RNA ligases. ''Proc Natl Acad Sci USA'' 91(14): 6624–6628. The transfer RNA (tRNA) for histidine is unique among eukaryotic tRNAs in re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA Ligase
In enzymology, an RNA ligase (ATP) () is an enzyme that catalyzes the chemical reaction ''ATP + (ribonucleotide)n + (ribonucleotide)m \rightleftharpoons AMP + diphosphate + (ribonucleotide)n+m''. Their three substrates are ATP, (ribonucleotide)n and (ribonucleotide)m, and their three products are AMP, diphosphate and (ribonucleotide)n+m. These enzymes belong to the family of ligases, specifically those forming phosphoric-ester bonds. The systematic name of this enzyme class is poly(ribonucleotide):poly(ribonucleotide) ligase (AMP-forming). Other names in common use include polyribonucleotide synthase (ATP), RNA ligase, polyribonucleotide ligase and ribonucleic ligase. As of late 2007, two structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ... have been solved for this c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Ligase
DNA ligase is a type of enzyme that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. It plays a role in repairing single-strand breaks in duplex DNA in living organisms, but some forms (such as DNA ligase IV) may specifically repair double-strand breaks (i.e. a break in both complementary strands of DNA). Single-strand breaks are repaired by DNA ligase using the complementary strand of the double helix as a template, with DNA ligase creating the final phosphodiester bond to fully repair the DNA. DNA ligase is used in both DNA repair and DNA replication (see '' Mammalian ligases''). In addition, DNA ligase has extensive use in molecular biology laboratories for recombinant DNA experiments (see '' Research applications''). Purified DNA ligase is used in gene cloning to join DNA molecules together to form recombinant DNA. Enzymatic mechanism The mechanism of DNA ligase is to form two covalent phosphodiester bonds between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superfamily (biology)
In biology, taxonomic rank (which some authors prefer to call nomenclatural rank because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of organisms (a ''taxon'') in a hierarchy that reflects evolutionary relationships. Thus, the most inclusive clades (such as Eukarya and Animalia) have the highest ranks, whereas the least inclusive ones (such as ''Homo sapiens'' or '' Bufo bufo'') have the lowest ranks. Ranks can be either relative and be denoted by an indented taxonomy in which the level of indentation reflects the rank, or absolute, in which various terms, such as species, genus, family, order, class, phylum, kingdom, and domain designate rank. This page emphasizes absolute ranks and the rank-based codes (the Zoological Code, the Botanical Code, the Code for Cultivated Plants, the Prokaryotic Code, and thCode for Viruses require them. However, absolute ranks are not r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleotidyltransferase
Nucleotidyltransferases are transferase enzymes of phosphorus-containing groups, e.g., substituents of nucleotidylic acids or simply nucleoside monophosphates. The general reaction of transferring a nucleoside monophosphate moiety from A to B, can be written as: :A-P-N + B \rightleftharpoons A + B-P-N For example, in the case of polymerases, A is pyrophosphate and B is the nascent polynucleotide. They are classified under EC number 2.7.7 and they can be categorised into: # Uridylyltransferases, which transfer uridylyl- groups # Adenylyltransferases, which transfer adenylyl- groups # Guanylyltransferases, which transfer guanylyl- groups # Cytitidylyltransferases, which transfer cytidylyl- groups # Thymidylyltransferases, which transfer thymidylyl- groups Role in metabolism Many metabolic enzymes are modified by nucleotidyltransferases. The attachment of an AMP (adenylylation) or UMP (uridylylation) can activate or inactivate an enzyme or change its specificity (see figure) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalyze
Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. The rate increase occurs because the catalyst allows the reaction to occur by an alternative mechanism which may be much faster than the noncatalyzed mechanism. However the noncatalyzed mechanism does remain possible, so that the total rate (catalyzed plus noncatalyzed) can only increase in the presence of the catalyst and never decrease. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl Group
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many organic compounds. It is a very stable group in most molecules. While the methyl group is usually part of a larger molecule, bonded to the rest of the molecule by a single covalent bond (), it can be found on its own in any of three forms: methanide anion (), methylium cation () or methyl radical (). The anion has eight valence electrons, the radical seven and the cation six. All three forms are highly reactive and rarely observed. Methyl cation, anion, and radical Methyl cation The methylium cation () exists in the gas phase, but is otherwise not encountered. Some compounds are considered to be sources of the cation, and this simplification is used pervasively in organic chemistry. For ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanosine
Guanosine (symbol G or Guo) is a purine nucleoside comprising guanine attached to a ribose ( ribofuranose) ring via a β-N9- glycosidic bond. Guanosine can be phosphorylated to become guanosine monophosphate (GMP), cyclic guanosine monophosphate (cGMP), guanosine diphosphate (GDP), and guanosine triphosphate (GTP). These forms play important roles in various biochemical processes such as synthesis of nucleic acids and proteins, photosynthesis, muscle contraction, and intracellular signal transduction (cGMP). When guanine is attached by its N9 nitrogen to the C1 carbon of a deoxyribose ring it is known as deoxyguanosine. Physical and chemical properties Guanosine is a white, crystalline powder with no odor and mild saline taste. It is very soluble in acetic acid, slightly soluble in water, insoluble in ethanol, diethyl ether, benzene and chloroform. Functions Guanosine is required for an RNA splicing reaction in mRNA, when a "self-splicing" intron removes itself from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanosine Monophosphate
Guanosine monophosphate (GMP), also known as 5′-guanidylic acid or guanylic acid (conjugate base guanylate), is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside guanosine. GMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase guanine; hence it is a ribonucleotide monophosphate. Guanosine monophosphate is commercially produced by microbial fermentation. As an acyl substituent, it takes the form of the prefix guanylyl-. ''De novo'' synthesis GMP synthesis starts with D-ribose 5′-phosphate, a product of the pentose phosphate pathway. The synthesis proceeds by the gradual formation of the purine ring on carbon-1 of ribose, with CO2, glutamine, glycine, aspartate and one-carbon derivatives of tetrahydrofolate donating various elements towards the building of the ring. As inhibitor of guanosine monophosphate synthesis in experimental models, the glutamine analogue DON can be used.''Ahluwalia GS et al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MRNA
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein. mRNA is created during the process of Transcription (biology), transcription, where an enzyme (RNA polymerase) converts the gene into primary transcript mRNA (also known as pre-mRNA). This pre-mRNA usually still contains introns, regions that will not go on to code for the final amino acid sequence. These are removed in the process of RNA splicing, leaving only exons, regions that will encode the protein. This exon sequence constitutes mature mRNA. Mature mRNA is then read by the ribosome, and the ribosome creates the protein utilizing amino acids carried by transfer RNA (tRNA). This process is known as Translation (biology), translation. All of these processes form part of the central dogma of molecular biology, which describes the flow of geneti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
