Biomedical Engineering Reference
In-Depth Information
Figure 1
. Image of a 2D protein electrophoresis of a whole cell lysate of colorectal cancer
cells. Obtained from the SWISS-2DPAGE database (17) at http://us.expasy.org/ch2d/cours2d/
gels24.html. Reprinted with permission from the Swiss Institute of Bioinformatics, Geneva,
Switzerland.
hour have been achieved. However, as in the case of two-dimensional gel elec-
trophoresis, insoluble proteins and proteins of very low abundance are still a
problem. (Unfortunately, many key regulators of cellular processes fall in the
latter category.)
In typical applications of either 2D electrophoresis or direct mass-
spectrometry, the primary goal is not identification of a large number of proteins
expressed in one cell or tissue, but a comparison of protein expression. For ex-
ample, one may be interested in how particular environmental conditions, such
as excessive heat or drought, affect protein expression, in order to identify pro-
tein networks that might contribute to heat or drought tolerance. To do so, one
needs to compare protein expression between an experimentally manipulated
environmental condition and a control (unmanipulated) condition. Another ap-
plication is the identification of gene functions through the effects that mutations
in a gene of interest have on the expression of other genes. Such mutant studies
are pursued to obtain information about potential genetic and physical interac-
tions of the gene's products. Comparative analysis of protein expression also has
many uses in biomedicine, especially in disease diagnosis. Diseased tissue can
