Protein analysis or proteomics

Proteomics is a recent science that studies proteins. The term "proteome", proposed in 1995 , refers to all the proteins expressed by the genome of a cell, tissue or organ at a given moment in its development.

Although the sequencing of the human genome is now complete, the study of the genome has its limits. Knowledge of the genome is not sufficient to understand the complexity of cell function. The same genome leads to the expression of several proteomes, depending on the stages of the cell cycle and the cell's pathophysiological state. Finally, proteins can undergo numerous modifications independently of the expression of the encoding gene alone. Proteomic analysis therefore provides a dynamic description of the regulation of gene expression, through the study of proteins and their post-translational modifications.

Proteomic analysis has two fields of application: on the one hand, the identification of proteins for a given organism (intracellular localization, protein-protein interactions) and, on the other, knowledge of protein expression levels and the effects of external agents (pathologies, drug treatments, environmental factors, etc.).

Proteomic analysis is mainly based on a methodology combining two-dimensional electrophoresis (2D-PAGE), a technique with very high resolving power, and mass spectrometry. A classic proteomic analysis can be summarized as follows:

• extraction of proteins from a given biological material ;

• protein separation by electrophoresis ;

• analysis of these proteins by mass spectrometry.

In addition to these three steps, we will complete this presentation with a description of data processing (querying databases to identify proteins and/or their modifications), an introduction to proteomic approaches based on alternative techniques, and finally on the different approaches to a proteomic study and the different techniques for quantifying proteins.