Half-life Assay by Proteomic Approaches

The protein complement expressed by an organism's genome, or in the case of multicellular organisms, the protein complement produced by tissue or differentiated cells, has been characterized as the proteome. Half-life assay by proteomic approach can be a database repository, a biological assay, or a tool for biological study. Although mass spectrometry is an effective tool for many different protein investigations, its use is primarily limited to qualitative methods. In response to the recent realization of the importance of quantitation in proteomics, mass spectrometric techniques based on stable isotope quantitation, such as stable isotope labeling in cell culture (SILAC), were developed. SILAC showed great promise for the simultaneous and automated identification and quantitation of complex protein mixtures. Given that the expression of genes and gene products can differ between tissues and that this expression can be influenced by a variety of physiological signals, both stimulatory and inhibitory, SILAC can be a useful tool for monitoring protein synthesis, turnover, and degradation under various physiological and experimental circumstances. Additionally, a temporal tracking of protein abundance can be facilitated by the use of various isotopic variants of an amino acid.

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