Codon regulatory

Pig. 3. Representation of promoter sites on the pro-enkephalin gene. The numbers represent the distance in nucleotides from the pro-enkephalin initiation codon the arrow indicates the direction of transcription. The TATA promoter box occurs immediately before the pro-enkephalin initiation site the AP-2 site, which binds immediate-early gene products, is 70 nucleotides upstream, and the CRE site, which binds a regulatory protein involved in cAMP induction of mRNA synthesis, is 107 nucleotides upstream from the initiation codon. The expanded section shows that the CRE site actually consists of two elements, ENKCRE-1 and ENKCRE-2, which separately confer cAMP sensitivity to pro-enkephalin mRNA synthesis. 

A structural gene is a linear sequence of codons which codes for a functional polypeptide, that is, a linear sequence of amino acids. Individual polypeptides may have a structural, enzymatic or regulatory role in the cell. Although the primary structure of DNA is the same in prokaryotes and eukaryotes, there are differences between the genes of these two types of organism, in internal structure, numbers and... 

G-CSF expression is controlled at both the transcriptional and posttranscrip-tional levels. A sequence of 300 nucleotides upstream of the initiation codon is conserved in both the murine and human genes, and this appears to contain three regulatory sites. G-CSF (and some other cytokine genes) may be constitutively transcribed by cells such as blood monocytes, fibroblasts and endothelial cells, but the mRNA may be short-lived (fi/2 < 15 min). The mRNA contains poly-AUUUA sequences in the untranslated region, and this motif is usually associated with mRNA instability. Indeed, such regions have also been identified in mRNA for GM-CSF, IL-1, IL-6, interferons, TNF, some growth factors, c-jun, c-fos, c-myc and c-myb. Upon the addi-... 

Translation of the information encoded in DNA, expressed as a particular nucleotide sequence, into a protein, expressed as an amino acid sequence, depends on the genetic code. In this code, sequences of three nucleotides (termed a codon) represent one of the 20 amino acids that compose the protein molecule. Because there are 64 codons which can be constructed for the four different bases, and only 20 different amino acids that are coded for, several amino acids may be coded for by more than one codon. There are also three codons, called stop codons, that terminate the transfer of information. Furthermore, although all cells contain the same complement of genes, certain cells (for example, the neurons) have specialized genes that encode specific proteins for the synthesis of specific transmitters. The expression of such genes is under the control of regulatory proteins called transcription factors which control the transcription of mRNAs from the genes they control. 

The 5 upstream region of the MnP-1 gene contains a TATAAA element 81 bp upstream of the translation initiation codon. In addition, three inverted CCAAT elements (ATTGG) ( ) are found at positions -181, -195, and -304 with respect to the initiation codon. We are analyzing the 5 upstream sequence of the MnP-1 gene for other possible regulatory sequence elements. 

The fimction of eIF-2 is illustrated schematically in Fig. 1.55. eIF-2 belongs to the superfamily of regulatory GTPases (see ch. 5). elF-2 fulfills the task of bringing the methionyl-initiator-tRNA to the 40S subimit of the ribosome. The active eIF-2 GTP form binds the methionyl-initiator-tRNA, associates with the cap structure of the mRNA, then commences to scan along the mRNA. Once an AUG codon is encoimte-red, the boimd GTP is hydrolyzed to GDP, resulting in the dissociation of the... 

Cp4 and the secreted segment to the 5 border of the first membrane exon the donor splice site lies within a GGU glycine codon that is retained in ps mRNA. Which form of mRNA is produced depends on competition between splicing and polyadenylation at the p.s and pm poly(A) sites (Peterson and Perry, 1986 Tsurushita et al., 1987 Galli et al., 1988 Peterson and Perry, 1989). The balance between the two mRNA products determines the proportion of membrane and secreted IgM. Activation of the B lymphocyte appears to tip the balance in favor of secretion, but the regulatory signals are not known. 

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