Spacer regions

In summary, a DNA-supported asymmetric interface located within the DNA-binding domains of these nuclear receptors provides the molecular basis for receptor heterodimers to distinguish between closely related response elements. RXR can provide a repertoire of different dimerization surfaces, each one unique for a specific partner, allowing dimers to form that are adapted to the length of the spacer region in their corresponding response elements. 

Figure 10.12 Response elements for heterodimers of the nuclear receptor for ds-retinoic acid (RXR) with the receptors for vitamin D (VDR), thyroid hormone (TR) and trans-retinoic acid (RAR). The half-sites of these response elements have identical nucleotide sequences and are organized as direct repeats. They differ in the number of base pairs in the spacer region between the half-sites. This difference forms the basis for the ability of the heterodimers to discriminate between the different response elements.

Seurinck,S. Verstraete,W. Siciliano, S. D. Use of 16S-23S rRNA intergenic spacer region PCR and repetitive extragenic palindromic PCR analyses of Escherichia coli isolates to identify nonpoint fecal sources. Appl. Environ. Microbiol. 2003, 69,4942 1950. 

Johnson, Y. A. Nagpal, M. Krahmer, M. T. Fox, K. F. Fox, A. Precise molecular weight determination of PCR products of the rRNA intergenic spacer region using electrospray quadrupole mass spectrometry for differentiation of B. subtilis and... 

Wunschel, D. K. Fox, K. Black, G. Fox, A. Discrimination among the Bacillus cereus group, in comparison to B. subtilis, by structural carbohydrate profiles and ribosomal RNA spacer region PCR System. Appl. Microbiol. 1994,17, 625-635. 

This enzyme [EC 3.1.26.3], also known as RNase O and RNase D, catalyzes the endonucleolytic cleavage of RNA to 5 -phosphomonoesters. The enzyme cleaves multimeric tRNA precursors at the spacer region and is also involved in the processing of precursor rRNA, hnRNA, and early T7-mRNA. This enzyme can also act on double-stranded DNA. 

The spacer region of HDAC inhibitors has been the subject of optimization in several medicinal chemistry reports. Examples of a class of compounds having an aromatic moiety present in the spacer region are depicted in Fig. 12 [75-77]. 

Introduction of a heteroaromatic group in the spacer proved beneficial in the work by Johnson Johnson researchers Arts et al. [83] and Angibaud et al. [84]. Optimization of the initial lead, having a 1,4-substituted phenyl present in the spacer region (Fig. 15, entry 1), was done by replacing this R... 

Le Jeune, C. and Fonvaud-Funel, A. (1997). Sequence of DNA 16S/23S spacer region of Leuconostoc oenos (Oenococcus oeni) Application to strain differentiation. Res. Microbiol. 148, 79-86. 

E. coli contains clusters of up to seven tRNA genes separated by spacer regions, as well as tRNA genes within ribosomal RNA transcription units. Following transcription, the primary RNA transcript folds up into specific stem-loop structures and is then processed by ribonucleases D, E, F and P in an ordered series of reactions to release the individual tRNA molecules. 

A ribosome display construct (the library in the ribosome display format) can be prepared completely in vitro either by ligation of the DNA library to the spacer region or by assembly PCR of the DNA library and the spacer. All the above-mentioned features, which are important for ribosome display (T7 promoter, ribosome binding site, and stem-loop structure), are then introduced by PCR (Fig. 3). 

In both eukaryotic and prokaryotic cells, large precursors to rRNA are transcribed and processed to produce the mature rRNAs. Processing involves methylation of bases and/or ribose and endolytic cleavage to cut out unwanted sequences. The eukaryotic products are the 18, 5.8, and 28 S rRNAs. In prokaryotes, the final products are the 16 S rRNA, a spacer region that includes one or two tRNAs, the 23 S rRNA, and the 5 S rRNA and, in some instances, one or two additional tRNAs. 

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