ABSTRACT
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Proteomics (protein + omics) simply means many or groups of proteins. However, it refers to identification and quantification of complete sets of proteins expressed by the genome at any given time in a cell. The field has been divided into at least two disciplines: functional proteomics, which refers to the determination of the function of all the proteins encoded in a genome; and structural proteomics, which hopes to determine the structures of all these proteins [1,2]. Proteomics is therefore
“1167_C012” — — #2
about understanding the structure and function of all proteins [3]. As a result, its application in biological sciences, especially cancer research and therapeutics, has been unprecedented [4-9]. The key reasons behind the progress and interest in proteomics are the facts that (1) protein expression levels are not always predictable from mRNA expression levels, (2) proteins undergo a variety of posttranslational modifications, and (3) proteins are dynamic and carry out a majority of the cellular functions [10]. Many cellular and environmental factors may alter gene and protein expression, and none of these factors can be identified solely from examining gene expression. On the other hand, proteins respond to altered conditions by changing their location within the cell, undergoing proteolysis, and adjusting their stability as well as changing their physical interactions with other macromolecules. The current cDNA microarray technology does not provide information regarding posttranscriptional control of gene expressions, changes in protein expression levels, or changes in protein synthesis and degradation rates. Therefore, a detailed understanding of the control of gene requires information about mRNA and protein expression levels.
