Sierra Acai Company
Sierra Acai Company
Open 7 Days a Week
MonaVie Independent Distributor
Distributor Training
Shop Online
Enroll Now
Buy Wholesale and maintain an Active status for 2 months and we will refund your $39 Distributor Fee
Friends
Buy Wholesale and maintain an Active status for 2 months and we will refund your $39 Distributor Fee
20-September-2008 09:29:09 - Transfer RNA Transfer RNA From PDB 6tna Proteopedia 6tna Transfer RNA From PDB 6tna Proteopedia 6tna Transfer RNA abbreviated tRNA is a small RNA usually about 74-95 nucleotides that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. It has a 3' terminal site for amino acid attachment. This covalent linkage is catalyzed by an aminoacyl tRNA synthetase. It also contains a three base region called the anticodon that can base pair to the corresponding three base codon region on mRNA. Each type of tRNA molecule can be attached to only one type of amino acid, but because the genetic code contains multiple codons that specify the same amino acid, tRNA molecules bearing different anticodons may also carry the same amino acid. Contents 1 Structure 2 Anticodon 3 Aminoacylation 4 Binding to ribosome 5 tRNA genes 6 History 7 References 8 See also 9 External links Structure Structure of tRNA. CCA tail in orange, Acceptor stem in purple, D arm in red, Anticodon arm in blue with Anticodon in black, T arm in green. Structure of tRNA. CCA tail in orange, Acceptor stem in purple, D arm in red, Anticodon arm in blue with Anticodon in black, T arm in green. tRNA has primary structure, secondary structure usually visualized as the cloverleaf structure, and tertiary structure all tRNAs have a similar L-shaped 3D structure that allows them to fit into the P and A sites of the ribosome. The 5'-terminal phosphate group. The acceptor stem is a 7-bp stem made by the base pairing of the 5'-terminal nucleotide with the 3'-terminal nucleotide which contains the CCA 3'-terminal group used to attach the amino acid. The acceptor stem may contain non-Watson-Crick base pairs. The CCA tail is a CCA sequence at the 3' end of the tRNA molecule. This sequence is important for the recognition of tRNA by enzymes critical in translation. In prokaryotes, the CCA sequence is transcribed. In eukaryotes, the CCA sequence is added during processing and therefore does not appear in the tRNA gene. The D arm is a 4 bp stem ending in a loop that often contains dihydrouridine. The anticodon arm is a 5-bp stem whose loop contains the anticodon. The T arm is a 5 bp stem containing the sequence TΨC where Ψ is a pseudouridine. Bases that have been modified, especially by methylation, occur in several positions outside the anticodon. The first anticodon base is sometimes modified to inosine derived from adenine or pseudouridine derived from uracil. Anticodon An anticodon1 is a unit made up of three nucleotides that correspond to the three bases of the codon on the mRNA. Each tRNA contains a specific anticodon triplet sequence that can base-pair to one or more codons for an amino acid. For example, one codon for lysine is AAA; the anticodon of a lysine tRNA might be UUU. Some anticodons can pair with more than one codon due to a phenomenon known as wobble base pairing. Frequently, the first nucleotide of the anticodon is one of two not found on mRNA: inosine and pseudouridine, which can hydrogen bond to more than one base in the corresponding codon position. In the genetic code, it is common for a single amino acid to be specified by all four third-position possibilities; for example, the amino acid glycine is coded for by the codon sequences GGU, GGC, GGA, and GGG. To provide a one-to-one correspondence between tRNA molecules and codons that specify amino acids, 61 tRNA molecules would be required per cell. However, many cells contain fewer than 61 types of tRNAs because the wobble base is capable of binding to several, though not necessarily all, of the codons that specify a particular amino acid.2 Aminoacylation Aminoacylation is the process of adding an aminoacyl group to a compound. It produces tRNA molecules with their CCA 3' ends covalently linked to an amino acid. Each tRNA is aminoacylated or charged with a specific amino acid by an aminoacyl tRNA synthetase. There is normally a single aminoacyl tRNA synthetase for each amino acid, despite the fact that there can be more than one tRNA, and more than one anticodon, for an amino acid. Recognition of the appropriate tRNA by the synthetases is not mediated solely by the anticodon, and the acceptor stem often plays a prominent role. Reaction: amino acid + ATP → aminoacyl-AMP + PPi aminoacyl-AMP + tRNA → aminoacyl-tRNA + AMP Binding to ribosome The ribosome has three binding sites for tRNA molecules: the A, P, and E sites. During translation the A site binds an incoming aminoacyl-tRNA as directed by the codon currently occupying this site. This codon specifies the next amino acid to be added to the growing peptide chain. The A site only works after the first aminoacyl-tRNA has attached to the P site. The P-site codon is occupied by peptdyl-tRNA that is a tRNA with multiple amino acids attached as a long chain. The P site is actually the first to bind to aminoacyl tRNA. This tRNA in the P site carries the chain of amino acids that has already been synthesized. The E site is occupied by the empty tRNA as it is about to exit the ribosome. tRNA genes Organisms vary in the number of tRNA genes in their genome. The nematode worm C. elegans, a commonly used model organism in genetics studies, has 29,647 3 genes in its nuclear genome, of which 620 code for tRNA.45 The budding yeast Saccharomyces cerevisiae has 275 tRNA genes in its genome. In the human genome, which according to current estimates has about 27,161 genes 6 in total, there are about 4,421 non-coding RNA genes, which include tRNA genes. There are 22 mitochondrial tRNA genes;7 497 nuclear genes encoding cytoplasmic tRNA molecules and there are 324 tRNA-derived putative pseudogenes.8 Cytoplasmic tRNA genes can be grouped into 49 families according to their anticodon features. These genes are found on all chromosomes, except 22 and Y chromosome. High clustering on 6p is observed 140 tRNA genes, as well on 1 chromosome.8 tRNA molecules are transcribed in eukaryotic cells by RNA polymerase III,9 unlike messenger RNA which is transcribed by RNA polymerase II. pre-tRNAs contain introns; in bacteria these self-splice, whereas in eukaryotes and archaea they are removed by tRNA splicing endonuclease.10 History The existence of tRNA was first hypothesized by Francis Crick, based on the assumption that there must exist an adapter molecule capable of mediating the translation of the RNA alphabet into the protein alphabet. Significant research on structure was conducted in the early 1960s by Alex Rich and Don Caspar, two researchers in Boston, the Jacques Fresco group in Princeton University and a United Kingdom group at King's College London.11 A later publication reported the primary structure in 1965 by Robert W. Holley. The secondary and tertiary structures were derived from X-ray crystallography studies reported independently in 1974 by American and British research groups headed, respectively, by Alexander Rich and Aaron Klug. References ^ Felsenfeld G, Cantoni G 1964. Use of thermal denaturation studies to investigate the base sequence of yeast serine sRNA. Proc Natl Acad Sci U S A 51: 818-26. doi:10.1073/pnas.51.5.818. PMID 14172997. ^ Lodish H, Berk A, Matsudaira P, Kaiser CA, Krieger M, Scott MP, Zipursky SL, Darnell J. 2004. Molecular Biology of the Cell. WH Freeman: New York, NY. 5th ed. ^ WormBase web site, http://www.wormbase.org, release WS187, date 25-Jan-2008. ^ Spieth, J. and Lawson, D. Overview of gene structure January 18, 2006, WormBook, ed. The C. elegans Research Community, WormBook, doi/10.1895/wormbook.1.65.1, http://www.wormbook.org ^ Hartwell LH, Hood L, Goldberg ML, Reynolds AE, Silver LM, Veres RC. 2004. Genetics: From Genes to Genomes 2nd ed. McGraw-Hill: New York, NY. p 264. ^ Ensembl release 48 - Dec 2007 http://www.ensembl.org ^ Ibid. p 529. ^ a b Lander E. et al. 2001. Initial sequencing and analysis of the human genome. Nature 409 6822: 860-921. doi:10.1038/35057062. PMID 11237011. ^ White RJ 1997. Regulation of RNA polymerases I and III by the retinoblastoma protein: a mechanism for growth control?. Trends in Biochemical Sciences 22 3: 77-80. doi:10.1016/S0968-00049610067-0. ^ Abelson J, Trotta CR, Li H 1998. tRNA Splicing. J Biol Chem 273 21: 12685-12688. doi:10.1074/jbc.273.21.12685. PMID 9582290. ^ Brian F.C. Clark October 2006. The crystal structure of tRNA. J. Biosci. 31 4: 453-7. doi:10.1007/BF02705184. PMID 17206065. See also mRNA tmRNA non-coding RNA and introns translation Kim Sung-Hou wobble hypothesis External links tRNA could be the cause of heart attack Sprinzl tRNA compilation Collection of tRNAs identified from complete genomes Molecule of the Month © RCSB Protein Data Bank: Transfer RNA Aminoacyl-tRNA Synthetases Elongation Factors v d e Types of nucleic acids Constituents Nucleobases | Nucleosides | Nucleotides | Deoxynucleotides Ribonucleic acids RNA | mRNA pre-mRNA/hnRNA | tRNA | rRNA | aRNA | gRNA | miRNA | ncRNA | piRNA | shRNA | siRNA | snRNA | snoRNA | stRNA | ta-siRNA | tmRNA Deoxyribonucleic acids DNA | cDNA | gDNA | msDNA | mtDNA Nucleic acid analogues GNA | LNA | PNA | TNA | morpholino Cloning vectors phagemid | plasmid | lambda phage | cosmid | P1 phage | fosmid | BAC | YAC | HAC Major families of biochemicals Saccharides | Carbohydrates | Glycosides | | Amino acids | Peptides | Proteins | Glycoproteins | | Lipids | Terpenes | Steroids | Carotenoids Alkaloids | Nucleobases | Nucleic acids | | Enzyme cofactors | Flavonoids | Polyketides | Tetrapyrroles Retrieved from http://en..org/wiki/Transfer_RNA Categories: RNA | Protein biosynthesis | Non-coding RNA Views Article Discussion this page History Personal tools Log in / create account Navigation Main page Contents Featured content Current events Random article Search Go Search Interaction Community portal Recent changes Contact Donate to Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page Languages БългарÑ?ки Català Česky Dansk Deutsch Eesti Español Français Italiano עברית Latina Lietuvių Magyar Nederlands 日本語 Occitan Polski Português РуÑ?Ñ?кий SlovenÄ?ina СрпÑ?ки / Srpski Svenska Türkçe ä¸æ–‡ This page was last modified on 8 August 2008, at 03:02
39 Reasons to Drink Acai Juice Every Day
What is MonaVie - Watch the 8-minute video
Discovering MonaVie video
The Power of You video
Log into your Wholesale MonaVie Account
So many of us do not eat a balanced diet, get enough sleep, have too much stress, or are impacted with toxins and pollutants. Drinking 2 ounces of MonaVie twice a day will help your body detoxify as well as build your immune system. Its the smartest thing you can do for yourself, so start today. Buying MonaVie through our company guarantees you support 7 days a week and, if you would like to share MonaVie with your family and friends we will guide you from start to finish.
1. Click on Enroll Now (30 - 55% off retail price)
2. Pay $39 for your Wholesale ID number.
3. NO minimum order required.
4. MonaVie is delivered to your door in 3 to 5 days.