Translational open reading frame

A stretch of DNA that is transcribed as a single continuous RNA strand is called a transcription unit. A unit of transcription may contain one or more sequences encoding different polypeptide chains (translational open reading frames, ORF) or cistrons. The transcription unit is sometimes termed the primary transcript, pre-messenger RNA or heterogeneous nuclear RNA (hnRNA). The primary transcript is further processed to produce mRNA in a form that is relatively stable and readily participates in translation. In order to understand the primary need for processing of this RNA, the biochemical definition of a gene must be discussed. 

Figure 1. The organization of catalytic and non-catalytic domains in cellulases from C. fimi and other bacteria. CfCenA, B and C, and CfCex are the endo- and exo-p- 1, 4-glucanases of C. fimi, ClfX is a translated open reading frame from Cellulomonas flavigena (29), CtEGD and PfEndA are endo-p-1, 4-glucanases from Clostridium thermocellum and Pseudomonas fluorescens, respectively (30,31), The primary structures are drawn approximately to scale and are numbered from the amino terminus of the mature protein ClfX is numbered from the start of the open reading frame. Unshaded areas represent catalytic domains, cross-hatched areas indicate cellulose-binding domains, repeated blocks of amino acids are stippled, and black areas represent linker regions.

Tel element of Caenorhabditis elegans (Fig. 2). No similarity with other transposable elements from D. melanogaster was found in the search. This is because the NBRF database does not contain all translations of open reading frames in DNA sequences. In fact it is possible to find similarity between the translated open reading frames of two Hb elements of D. 

Figure 7.5 Model of ferritin (and erythroid a-aminolaevulinate synthase) translation/ribosome binding regulation by IRP. In (a), with IRP not bound to the IRE (1) binding of the 43S preinitiation complex (consisting of the small ribosomal 40S subunit, GTP and Met-tRNAMet) to the mRNA is assisted by initiation factors associated with this complex, as well as additional eukaryotic initiation factors (elFs) that interact with the mRNA to facilitate 43S association. Subsequently (2), the 43S preinitiation complex moves along the 5 -UTR towards the AUG initiator codon, (3) GTP is hydrolysed, initiation factors are released and assembly of the 80S ribosome occurs. Protein synthesis from the open reading frame (ORF) can now proceed. In (b) With IRP bound to the IRE, access of the 43S preinitiation complex to the mRNA is sterically blocked. From Gray and Hentze, 1994, by permission of Oxford University Press.

Poyry, T. A., Kaminski, A., and Jackson, R. J. (2004). What determines whether mammalian ribosomes resume scanning after translation of a short upstream open reading frame Genes Dev. 18, 62—75. 

Morris, D. R., and Geballe, A. P. (2000). Upstream open reading frames as regulators of mRNA translation. Mol. Cell Biol. 20, 8635-8642. 

To obtain maximal protein productivity, it is necessary to construct an expression clone in which a protein coding region (open reading frame, mature region, domain, etc.) obtained from a cDNA of interest is inserted into the MCS of the pTD 1 vector. Typically, expression of the target protein at about 35-50 pg per mL of the translation reaction mixture can be obtained by using mRNA transcribed from the expression clone and the Transdirect insect cell kit. Furthermore, the expression clone can be effectively combined with other eukaryotic cell-free protein synthesis systems, such as rabbit reticulocyte lysate and wheat germ systems (tee Note 3). 

Terms in bold are defined aminoacyl-tRNA 1035 aminoacyl-tRNA synthetases 1035 translation 1035 codon 1035 reading frame 1036 initiation codon 1038 termination codons 1038 open reading frame (ORF) 1039 anticodon 1039 wobble 1041... 

When tryptophan levels are high, the ribosome quickly translates sequence 1 (open reading frame encoding leader peptide) and blocks sequence 2 before sequence 3 is transcribed. Continued transcription leads to attenuation at the terminator-like attenuator structure formed by sequences 3 and 4. 

Functional" as used here for the human loci means rearranged in vivo with a sequence appropriate for transcription and translation into a stable protein (see Tomlinson et al., 1995). A gene segment may have an open reading frame and no obvious defect, but is not counted as functional unless it is detected as a MD)/ rearrangement that appears to encode a protein that can form a stable three-dimensional structure. 

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