Differential proteins

Figure 3.2. Stable isotope labeling for quantifying differential protein expression. Cell populations are grown in either 14N or 15N containing medium. Protein lysates are fractionated and separated by 2D gel electrophoresis. Protein spots are excised, digested with trypsin and the mass of the resulting peptides is determined by mass spectrometry. The presence of 15N results in a shift and creates two peaks for each peptide. The ratio of intensities of the peaks is indicative of the relative expression levels of the proteins. Spot A contains a protein that is expressed at similar levels in both cell pools. Spot B contains a protein that is expressed at higher levels in cell pool 2. Figure adapted from Oda et al. (1999).

Chevalier S et al. Proteomic analysis of differential protein expression in primary hepatocytes induced by EGF, tumour necrosis factor alpha or the peroxisome pro-liferator nafenopin. Eur J Biochem 2000 267 4624-4634. 

FIGURE 15.3 Outline of experimental protocol used for ICAT differential protein expression profiling. Protein mixtures from two cell populations are labeled with light or heavy isotopic versions of a cleavable ICAT reagent. Labeled proteins are combined, subject to multidimensional separation by SCX, RP, and avidin affinity chromatography, then analyzed by tandem MS for peptide and protein identification. Based on the relative ratio of the two isotopically labeled peptides, a relative abundance of protein expression can be determined. 

IFl-3). In contrast, eukaryotic initiation is a rather complex process involving a large number of initiation factors (elFs, Table 1). This is also the stage of eukaryotic ribosomal protein synthesis, which is most highly regulated to achieve differential protein expression. Elaborating the details of eukaryotic initiation is beyond the scope of this chapter. 

In all forms of glomerular nephritis in tropical populations in Africa, there was increased protein in the urine. In the selective proteinuria of the nephrotic syndrome most of the protein was mainly albumin and transferrin, with lower concentrations of IgG and other globulins. On the other hand, the urine of the nonselective proteinuria of the nephrotic syndrome is characterized by much higher concentrations of IgG, IgA, a2-macroglobulins, and some IgM. Differential protein clearance to establish selectivity of proteinuria has been discussed above. 

C7. Chandra, R. K., Manchanda, S. S., Srivastava, R. N., and Soothill, J. F., Differential protein clearances in Indian children with the nephrotic syndrome. Arch. Dis. Childhood 45, 491-495 (1970). 

Proteomics includes a variety of technologies that include differential protein display on gels, protein chips, quantitation of protein amoimts, analysis of post-translational modifications, characterization of protein complexes and networks and bioinformatics. All this information in combination with genome and phenotype studies will ultimately yield a comprehensive picture of a cellular or tissue proteome (Wasinger and Corthals 2002). 

Human myeloid leukemia cell differentiation protein Mcl-l Mouse Bid... 

C Vasseur, J Labadie, M Elebraud. Differential protein expression by Pseudomonas fragi submitted to various stresses. Electrophoresis 20 2204-2213, 1999. 

FIGURE 7 Group B streptococcus infection-induced differential protein expression in nonhuman primate (A) and human (B) amniotic fluid samples by surface-enhanced laser desorption/ionization (SELDI-TOF MS) using normal-phase protein chip arrays. Spectrum from 2.5 to 15 kDa collected at 235 nm laser intensity. Detailed spectra show increased expression of the 3.5 and 10.8 kDa peaks between control and infected. Arrows indicate the unique peaks represented by polypeptides overexpressed in infection. 

Proteins analysis by 2-D electrophoresis and identification of differential proteins by MALDI-TOF-TOF... 

General consensus has sub-divided proteomics into three main areas, Expression Proteomics, Functional Proteomics, and Structural Proteomics. Expression Proteomics (sometimes called differential-expression proteomics) involves the analysis of differential protein expression by protein... 

Another challenge is the delivery of a biopharmaceutical to its site of action, as the injection of molecules in solution leads to a partitioning of the molecules according to their physicochemical properties. One approach to deliver particles injected intravenously is based on the concept of differential protein adsorption. After injection the particles adsorb blood proteins according to physicochemical surface properties of the particles. The adsorbed proteins determine the cells to which the particles will be directed (Muller and Keck, 2004). 

At present, there are advanced difference gel electrophoresis (DOGE) Systems and 2-D fluorescence difference gel electrophoresis (2-D DIGE) which enable the analyst to use simultaneously modern (more precise) methods of fluorescent analysis with 2-D electrophoresis (using internal patterns), aided by a fully integrated bioinformatics system. Such systems allow more complete differential protein analysis, while the application of internal standards eliminates differentiation between the intervals, thus ensuring that even the smallest differences will be detected irrespective of the multitude of components. This guarantees reproducibility of results and their statistical reliability. Such assays are one of the platforms employed in the research based on the proteomics method. 

Lexander H, Franzen B, Hirschberg D, Becker S, Hellstrom M, Bergman T, et al. Differential protein expression in anatomical zones of the prostate. Proteomics 2005 5(10)2570-2576. 

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