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Translation Initiation Codon
The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes and archaea and a ''N''-formylmethionine (fMet) in bacteria, mitochondria and plastids. The start codon is often preceded by a 5' untranslated region (5' UTR). In prokaryotes this includes the ribosome binding site. Decoding In all three domains of life, the start codon is decoded by a special "initiation" transfer RNA different from the tRNAs used for elongation. There are important structural differences between an initiating tRNA and an elongating one, with distinguish features serving to satisfy the constraints of the translation system. In bacteria and organelles, an acceptor stem C1:A72 mismatch guide formylation, which directs recruitment by the 30S ribosome into the P site; so-called "3GC" base pairs allow assembly into the 70S ribosome. In eukaryotes and archaea, the T stem prevents the elongation factors from bindi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homo Sapiens-mtDNA~NC 012920-ATP8+ATP6 Overlap
''Homo'' () is a genus of great ape (family Hominidae) that emerged from the genus ''Australopithecus'' and encompasses only a single extant species, ''Homo sapiens'' (modern humans), along with a number of extinct species (collectively called archaic humans) classified as either ancestral or closely related to modern humans; these include '' Homo erectus'' and '' Homo neanderthalensis''. The oldest member of the genus is '' Homo habilis'', with records of just over 2 million years ago. ''Homo'', together with the genus '' Paranthropus'', is probably most closely related to the species '' Australopithecus africanus'' within ''Australopithecus''.'''' The closest living relatives of ''Homo'' are of the genus '' Pan'' ( chimpanzees and bonobos), with the ancestors of ''Pan'' and ''Homo'' estimated to have diverged around 5.7–11 million years ago during the Late Miocene. ''H. erectus'' appeared about 2 million years ago and spread throughout Africa (debatab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihydrofolate Reductase
Dihydrofolate reductase, or DHFR, is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, using NADPH as an electron donor, which can be converted to the kinds of tetrahydrofolate cofactors used in one-carbon transfer chemistry. In humans, the DHFR enzyme is encoded by the ''DHFR'' gene. It is found in the q14.1 region of chromosome 5. There are two structural classes of DHFR, evolutionarily unrelated to each other. The former is usually just called DHFR and is found in bacterial chromosomes and animals. In bacteria, however, antibiotic pressure has caused this class to evolve different patterns of binding diaminoheterocyclic molecules, leading to many "types" named under this class, while mammalian ones remain highly similar. The latter (type II), represented by the plastid-encoded R67, is a tiny enzyme that works by forming a homotetramer. Function Dihydrofolate reductase converts dihydrofolate into tetrahydrofolate, a proton shuttle required for the de no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formylmethionine
''N''-Formylmethionine (fMet, HCO-Met, For-Met) is a derivative of the amino acid methionine in which a formyl group has been added to the amino group. It is specifically used for initiation of protein synthesis from bacterial and organellar genes, and may be removed post-translationally. fMet plays a crucial part in the protein synthesis of bacteria, mitochondria and chloroplasts. It is not used in cytosolic protein synthesis of eukaryotes, where eukaryotic nuclear genes are translated. It is also not used by Archaea. In the human body, fMet is recognized by the immune system as foreign material, or as an alarm signal released by damaged cells, and stimulates the body to fight against potential infection. Function in protein synthesis Translation fMet is required for efficient initiation of protein synthesis in most groups of bacteria. The 30S ribosome–mRNA complex specifically recruits tRNAs with a formylated amino acid – tRNAfMet attached to fMet in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amber Codon
Amber is fossilized tree resin. Examples of it have been appreciated for its color and natural beauty since the Neolithic times, and worked as a gemstone since antiquity."Amber" (2004). In Maxine N. Lurie and Marc Mappen (eds.) ''Encyclopedia of New Jersey'', Rutgers University Press, . Amber is used in jewelry and as a healing agent in folk medicine. There are five classes of amber, defined on the basis of their chemical constituents. Because it originates as a soft, sticky tree resin, amber sometimes contains animal and plant material as inclusions. Amber occurring in coal seams is also called resinite, and the term ''ambrite'' is applied to that found specifically within New Zealand coal seams. Etymology The English word ''amber'' derives from Arabic from Middle Persian 𐭠𐭭𐭡𐭫 (''ʾnbl'' /ambar/, “ambergris”) via Middle Latin ''ambar'' and Middle French ''ambre''. The word referred to what is now known as '' ambergris'' (''ambre gris'' or "gray ambe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kozak Consensus Sequence
The Kozak consensus sequence (Kozak consensus or Kozak sequence) is a Nucleic acid sequence, nucleic acid motif that functions as the protein Translation (biology), translation initiation site in most eukaryotic Messenger RNA, mRNA transcripts. Regarded as the optimum sequence for initiating translation in eukaryotes, the sequence is an integral aspect of protein regulation and overall cellular health as well as having implications in human disease. It ensures that a protein is correctly translated from the genetic message, mediating ribosome assembly and translation initiation. A wrong start site can result in non-functional proteins. As it has become more studied, expansions of the nucleotide sequence, bases of importance, and notable exceptions have arisen. The sequence was named after the scientist who discovered it, Marilyn Kozak. Kozak discovered the sequence through a detailed analysis of DNA genomic sequences. The Kozak sequence is not to be confused with the ribosomal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leucine
Leucine (symbol Leu or L) is an essential amino acid that is used in the biosynthesis of proteins. Leucine is an α-amino acid, meaning it contains an α-amino group (which is in the protonated −NH3+ form under biological conditions), an α-Carboxylic acid, carboxylic acid group (which is in the deprotonated −COO− form under biological conditions), and a side chain Isobutyl, isobutyl group, making it a Chemical polarity, non-polar Aliphatic compound, aliphatic amino acid. It is Essential amino acid, essential in humans, meaning the body cannot synthesize it; it must be obtained from the diet. Human dietary sources are foods that contain protein, such as meats, dairy products, soy products, and beans and other legumes. It is genetic code, encoded by the codons UUA, UUG, CUU, CUC, CUA, and CUG. Leucine is named after the Greek language, Greek word for "white": ''λευκός'' (''leukós'', "white"), after its common appearance as a white powder, a property it shares with many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Ribosome Entry Site
An internal ribosome entry site, abbreviated IRES, is an RNA element that allows for translation initiation in a cap-independent manner, as part of the greater process of protein synthesis. Initiation of eukaryotic translation nearly always occurs at and is dependent on the 5' cap of mRNA molecules, where the translation initiation complex forms and ribosomes engage the mRNA. IRES elements, however, allow ribosomes to engage the mRNA and begin translation independently of the 5' cap. History IRES sequences were first discovered in 1988 in the poliovirus (PV) and encephalomyocarditis virus (EMCV) RNA genomes in the laboratories of Nahum Sonenberg and Eckard Wimmer, respectively. They are described as distinct regions of RNA molecules that are able to recruit the eukaryotic ribosome to the mRNA. This process is also known as cap-independent translation. It has been shown that IRES elements have a distinct secondary or even tertiary structure, but similar structural features at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MKKS
McKusick–Kaufman/Bardet–Biedl syndromes putative chaperonin is a protein that in humans is encoded by the ''MKKS'' gene. This gene encodes a protein with sequence similarity to the chaperonin family. The encoded protein may have a role in protein processing in limb, cardiac and reproductive system development. Mutations in this gene have been observed in patients with Bardet–Biedl syndrome type 6 and McKusick–Kaufman syndrome McKusick–Kaufman syndrome (MKS) is a rare genetic condition caused by mutations in the '' MKKS'' gene, which affect how cells develop and function. It is named after Dr. Robert L. Kaufman and Victor McKusick, who studied the condition and helped .... Two transcript variants encoding the same protein have been identified for this gene. References External links GeneReviews/NIH/NCBI/UW entry on Bardet–Biedl syndromeGeneReviews/NIH/NCBI/UW entry on McKusick–Kaufman syndrome Further reading * * * * * * * * * * * * * * * * {{gene-20-s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MIER1
Mesoderm induction early response protein 1 is a protein that in humans is encoded by the ''MIER1'' gene. Interactions MIER1 has been shown to interact with HDAC1 Histone deacetylase 1 (HDAC1) is an enzyme that in humans is encoded by the ''HDAC1'' gene. Function Histone acetylation and deacetylation, catalyzed by multisubunit complexes, play a key role in the regulation of eukaryotic gene expression. .... References Further reading * * * * * * * * {{gene-1-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Reading Frame
In molecular biology, reading frames are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames will be "open" (the "reading", however, refers to the RNA produced by transcription of the DNA and its subsequent interaction with the ribosome in translation). Such an open reading frame (ORF) may contain a start codon (usually AUG in terms of RNA) and by definition cannot extend beyond a stop codon (usually UAA, UAG or UGA in RNA). That start codon (not necessarily the first) indicates where translation may start. The transcription termination site is located after the ORF, beyond the translation stop codon. If transcription were to cease before the stop codon, an incomplete protein would be made during translation. In eukaryotic genes with multiple exons, introns are removed and exons are then joined together after transcription to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RefSeq
The Reference Sequence (RefSeq) database is an open access, annotated and curated collection of publicly available nucleotide sequences (DNA, RNA) and their protein products. RefSeq was introduced in 2000. This database is built by National Center for Biotechnology Information (NCBI), and, unlike GenBank, provides only a single record for each natural biological molecule (i.e. DNA, RNA or protein) for major organisms ranging from viruses to bacteria to eukaryotes. For each model organism, ''RefSeq'' aims to provide separate and linked records for the genomic DNA, the gene transcripts, and the proteins arising from those transcripts. ''RefSeq'' is limited to major organisms for which sufficient data are available (121,461 distinct "named" organisms as of July 2022), while GenBank includes sequences for any organism submitted (approximately 504,000 formally described species). RefSeq categories RefSeq collection comprises different data types, with different origins, so it is neces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Messenger RNA
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 synthesizing a protein. mRNA is created during the process of 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. All of these processes form part of the central dogma of molecular biology, which describes the flow of genetic information in a biological system. As in DNA, genetic inf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
