Gene containment

Figure 9-31. Descriptor selection using a CA. The upper part of the figure shows the original set of descriptors, below which Is the chromosome, Those genes containing the value 1 are selected for the final set of descriptors, which is given at the bottom.

DNA from a gene contains hundreds to thousands of nucleotide units for which the sequence is needed in order to interpret its code. Sequencing methods require only small amounts (5 (tg) of purified DNA, which can be produced by cloning. Automated sequencers are available that can daily sequence DNA containing hundreds of nucleotide units. 

Biosynthesis. CRE is derived from a precursor of 196 amino acids (84,85). This gene contains one copy of CRE, which is flanked by double basic amino acids. The amino acid sequence of the CRE precursor suggests that it may arise from proteins related to POMC and neurophysins (31). The CRE precursor contains a cAMP responsive element which aHows stimulation of mRNA synthesis when intraceHular levels of cAMP are increased (86). 

A splice variant can arise when a gene contains at least two introns leading to the possibility that the DNA between them (an exon) may not be included in the final mRNA and protein product. Thus, the final protein product may exist in two forms one containing the amino-acid sequence encoded by the exon that is located between the introns in the original DNA, and another form in which the amino-acid sequence encoded by that exon has been spliced out . These two products are refened to as splice variants. 

The structure of all TK receptors is similar in terms of expression oiTACR genes, since all these genes contain five exons intercalated by four introns [1, 5]. Exon I encodes for the N-terminal extracellular tail, the first intracellular (IC1) and extracellular (EC1) loops and the first, second, and third transmembrane domains (TM1, TM2, and TM3). Exon II encodes for the second intracellular (IC2) and extracellular (EC2) loops and the fourth transmembrane domain (TM4). Exon III encodes for the fifth transmembrane domain (TM5) and the third intracellular loop (IC3). Exon IV encodes for the sixth and seventh transmembrane domains (TM6 and TM7) and the third extracellular loop. Exon V encodes for the C-terminal intracellular tail only. A schematic drawing of the amino acid sequences and TK receptor organization is shown in Fig. 1. 

Sequence derived from complete CG15920 gene contains two consensus repeat motifs GGRPSDSYGAPGGGN and GYSGGRPGGQDLG [187] with permission from The American Chemical Society, copyright 2009... 

If the nucleotide sequence of the gene containing the mutation is transcribed into an RNA molecule, then the RNA molecule will possess a complementary base change at this corresponding locus. 

Every gene contains DNA with a unique sequence of bases forming a genetic code containing the information an organism uses to iive and repiicate itseif Many years of research have resuited in an understanding of how the information content of DNA is transiated into particuiar biochemicai substances and how DNA repiicates. The processes inciude unwinding of the DNA doubie heiix so its code can be read or dupiicated. 

Fig. 24.4 Splicing of a messenger RNA molecule transcribed from a hypothetical insulin gene containing two introns.

Gonzalez E, Kulkami H, Bolivar H, et al. The influence of CCL3L1 gene-containing segmental duplications on HIV-l/AIDS susceptibility. Science 2005 307(5714) 1434-1440. 

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