You can read an accessible proteomics summary here for members of the public.
What is proteomics?
Proteomics can be broadly defined as the study of the proteome, which is “the entire complement of proteins that is (or can be) expressed by a cell, tissue, or organism.” (Oxford English Dictionary). Study of the proteome is of critical importance for understanding how biological systems behave. We and others have shown that cellular responses can lead to a high proportion of protein changes that are not just related to alterations in gene transcription, but can be attributed to altered rates of translation and protein degradation. Changes in protein activation state or localisation mediated by post-translational modifications can also have a major effect on biology. In this respect, the proteome is many times more complex than the genome or transcriptome; yet it offers a more accurate picture of cell function and behaviour (Figure 1).
Figure 1. The final composition of the proteome is regulated at multiple levels
Study of the proteome in its entirety in a single experiment, including all post-translational modifications (PTMs), is currently impossible. However, methods are available for analysis of protein expression, subcellular proteomes and specific post-translational modifications. This means that searching questions can be asked of the proteome on a global scale . To supplement these global approaches, targeted approaches can be developed to quantify and characterise specific proteins. This may enable the discovery of novel post-translational modifications or allow the quantification of proteins or specific-isoforms in their modified and/or unmodified forms without the use of antibodies.
 Coombs KM. (2011) Quantitative proteomics of complex mixtures. Expert Rev Proteomics. 8(5):659-677.[http://www.ncbi.nlm.nih.gov/pubmed/?term=21999835]