Tagging approaches

The isotope-coded affinity tag approach utilizes chemical labeling that allows quantitation when combined with mass spectrometry. ICAT is desirable because the chemical labeling takes advantage of the mass defects of monoisotopic stable isotopes. ICAT uses an ICAT reagent to differentially label protein samples on their cysteine residues. ICAT is advantageous because it permits the evaluation of low-abundance proteins and proteins at both extremes of molecular weights and isoelectric points.60... 

There are two strategies to use insertional mutagenesis for cloning purposes. One is the direct tagging approach. In this case a mutant, for example a spontaneous or chemically induced mutant, has already been identified, but no information on the nature of the mutated gene is available. 

Rabelo, E.M., Franco, G.R., Azevedo, V.A., Pena, H.B., Santos, T.M., Meira, W.S., Rodrigues, N.A., Ortega, J.M. and Pena, S.D. (1997) Update of the gene discovery program in Schistosoma mansoni with the expressed sequence tag approach. Memorias do Instituto Oswaldo Cruz 92, 625-629. 

Lee, J.S., Lee, J., Park, S.J. and Yung, T.S. (2003) Analysis of the genes expressed in Clonorchis sinensis adults using the expressed sequence tag approach. Parasitology Research 91, 283-289. 

Zimmer, J. S., Monroe, M. E., Qian, W. J., and Smith, R. D. (2006). Advances in proteomics data analysis and display using an accurate mass and time tag approach. Mass Spectrom. Rev. 25 450-482. 

Sethuraman M, McComb ME, Heibeck T, Costello CE, Cohen RA. Isotope-coded affinity tag approach to identify and quantify oxidant-sensitive protein thiols. Mol Cell Proteomics 2004 3 273-278. 

Even if the genes influencing a complex disease or trait all fall within haplotype blocks, the haplotype tagging approach will only be effective if the alleles associated with the disease or trait are relatively common. On the contrary, if the alleles associated with a complex disease are very rare (frequency < 1%) such variants are likely to be missed using the LD methods so far described. In fact, if a disease is caused by one or only a few genes with many distinct and individually very rare alleles, linkage analysis can perform better than association-based tests (50). 

Fig. 6. Schematic representation of the T-DNA tagging approach to identify regulators of TIA biosynthetic genes in C. roseus. For explanation, see the text...

Synthetic glycoproteins allow varied approaches to be tested. Davis et al. described the synthesis of glycoprotein probes able to detect mammalian brain inflammation and disease by using a dual tag approach [118]. They established two different orthogonal modifications in a selected protein (Scheme 19.11) [118, 119]. These modifications were introduced by disulfide formation at a single Cys position and by... 

Equation (4) above is the generally applicable expression for a singly labeled diet component when this component also contains a measurable level of isotope 2. For the case where the labeled component has been arranged so that its content of isotope 2 is negligible, as in the case of giving an oral dose of a highly enriched solution, as in the extrinsic tag approach, then Equation (5) is applicable. For situations where more than one component of the diet has been labeled by appropriate use of a selection of different stable isotopes, a more complex set of multiple simultaneous equations can be described (6) for determination of the absorption of zinc from the various labeled diet components. 

Shen, Y, Moore, R. J., Anderson, D. J., Zhang, R., Calvano, S. E., etal. (2005). Quantitative proteome analysis of human plasma following in vivo lipo-polysaccharide administration using 160/180 labeling and the accurate mass and time tag approach. Mol. Cell Proteomics 4, 700-709. 

W. J. Qian, M. B. Goshe, D. G. Camp II, L.-R. Yu, K. Tang, and R. D. Smith, Phos-phoprotein isotope-coded solid-phase tag approach for enrichment and quantitative analysis of phosphopeptides from complex mixtures, A aZ. Chem.15 (2003), 5441-5450. 

Figure 15.11. Peptide sequence elucidation using the sequence tag approach, with posterior...

Figure 15.11 also shows a scheme for the sequence tag approach in this scheme the definition used is that mi + m2 + m3 = M, where M is the peptide mass. Computer programs that use algorithms designed to search using this tag procedure are accessible on the internet.20... 

TABLE 15.8. Data Used to Search for a Peptide Sequence Using the Tag Approach"... 

Goshe, M.B. Conrads, T.P. Panisko, E.A. Angell, N.H. Veenstra, T.D. Smith, R.D. Phosphoprotein Isotope-Coded Affinity Tag Approach for Isolating and Quantifying Phosphopeptides in Proteome-wide Analyses, Anal. Chem. 73, 2578-2586 (2001). 

In most tagging approaches to catalyst design the ionic group is installed on the carbene ligands, i.e. the benzylidene fragment. Table 1.8 collects a few examples. 

Sequence Tag Approach to Protein Identification Using MS-MS Analysis... 

Recently, the Holst centre (http //www.holstcentre.com) demonstrated a 64 bit passive RFID-tag approaching technological requirements for item-level tagging [9]. The data could be read from 10 cm distance with a 780 bit/s data readout, fivefold higher as current state of the art bit rate in plastic electronics. 

Chiang MC et al (2007) Systematic uncovering of multiple pathways underlying the pathology of Huntington disease by an acid-cleavable isotope-coded affinity tag approach. Mol Cell Proteomics 6(5) 781-797... 

For each tagging approach, the orthogonal chemistry between the tags and compounds of interest has to be determined. Those compounds are chosen as encoding compounds that can be easily identified by well-established highly sensitive analytical microtechniques, even at very low concentrations. 

Phase Switching-Bipyridyl Tagging Approaches to Scavengers... 

Pooley K A, Healey C S, Smith P L, et al. (2006). Association of the progesterone receptor gene with breast cancer risk A single-nucleotide polymorphism tagging approach. Cancer Epidemiol. Biomarkers Prev. 15 675-682. 

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