Splicing, RNA

It is worth noting that in the case of the Cfi gene - unlike the genes for the other heavy chains (see Section 5.3. of this chapter) - the production of the mRNAs for the membrane and secreted forms of the heavy chain involves differential RNA splicing. This is because the carboxy-terminal ends of the secreted and membrane forms of the 8 polypeptide are encoded in distinct exons located 3 of the Cs3 exon. 

The question of stable co-expression of and other CH genes has also been raised. In particular, primary B cells have been described in which p and e are coexpressed from the same chromosome [129], As lymphocytes have Fc receptors for IgE, it is difficult to exclude the possibility that the IgM+ IgE+ cells seen in this work are not in fact IgM+ cells that have passively adsorbed secreted IgE onto their surface. B cells have also been identified that co-express lgM and IgA on their 

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FIGURE 14.23 RNA splicing in TetraAjimejta rRNA matnradon (a) the gnanosine-mediated reaction involved in the antocatalytic excision of the Tetrahymena rRNA intron, and (b) the overall splicing process. The cyclized intron is formed via nncleophilic attack of the 3 -OH on the phosphodiester bond that is 15 nncleotides from the 5 -GA end of the spliced-ont intron. Cyclization frees a linear 15-mer with a 5 -GA end. 

Yost, HJ. Lindquist, S. (1986). RNA splicing is interrupted by heat shock and is rescued by heat shock protein synthesis. Cell 45, 185-193. 

The processing of hnRNA molecules is a site for regulation of gene expression. Alternative patterns of RNA splicing result from tissue-specific adaptive and developmental control mechanisms. As mentioned... 

Eukaryotic mRNA synthesis results in a pre-mRNA precursor that contains extensive amounts of excess RNA (introns) that must be precisely removed by RNA splicing to generate functional, translatable mRNA composed of exonic coding and noncoding sequences. 

Splidng (1) Gene splicing manipulations, the object of which is to attach one DNA molecule to anodier (2) RNA splicing removal of inh ons fiom mRNA precursors. 

N10. Noguchi, T., Inoue, H., and Tanaka, T., The M,- and M2-type isozymes of rat pyruvate kinase are produced from the same gene by alternative RNA splicing. J. Biol. Chem. 261,13807-13812 (1986). 

Traynelis, S. F., Hartley M. and Heinemann, S. F. Control of proton sensitivity of the NMDA receptor by RNA splicing and polyamines. Science 268 873-876,1995. 

Figure 10.13 Phosphoryl-transfer reactions. The figure shows (a) nucleotide polymerization, (b) nucleic acid hydrolysis, (c) first cleavage of an exon-intron junction by group I ribozyme (d) and by a group II ribozyme, (e) strand transfer during transposition and (f) exon ligation during RNA splicing. (From Yang et al., 2006. Copyright 2006, with permission from Elsevier.)...

Figure 20.19 Summary of transcription, RNA splicing entry of mRNA into the cytosol and polypeptide formation. The difference in shading is to indicate the change from DNA to RNA. Splicing is just one of the four processes involved in the processing of the primary RNA transcript (Figure 20.20).

Marrs, K.A. and Walbot, V., Expression and RNA splicing of the maize glutathione S-transferase Bronze2 gene is regulated by cadmium and other stresses. Plant Physiol, 113, 93, 1997. 

In view of the short plasma half-life of 5-FU, most authors believe that continuous administration of 5-FU (CIFU) is the superior 5-FU schedule compared to bolus regimens. Continuous infusion of 5-FU seems to inhibit predominantly DNA s mthesis, whereas bolus administration of 5-FU inhibits RNA splicing and DNA synthesis, resulting in different toxicity and efficacy profiles (24,25). 

The recombination process is not as precise as the site-specific recombination described earlier, so additional variation occurs in the sequence at the V-J junction. This increases the overall variation by a factor of at least 2.5, thus the cells can generate about 2.5 X 1,200 = 3,000 different V-J combinations. The final joining of the V-J combination to the C region is accomplished by an RNA-splicing reaction after transcription, a process described in Chapter 26. 

RNA Splicing What is the minimum number of transesterification reactions needed to splice an intron from an mRNA transcript Explain. 

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