Functional Proteomics and Proteome Database

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FUNCTIONAL PROTEOMICS

Genome of an organism certainly provides a wealth of information. As recently several genomes have been sequenced, the current challenge has been shifted to study function of all proteins coded by genome (proteome). The goal of proteome research is not easy because many difficulties were faced when moving from genome to proteome research. Genome is comparatively static in nature than proteome of an organism; protein expression profiles change several times during the cell cycle and are heavily affected by a number of intracellular and extracellular stimuli (temperature, stress, apoptotic signals, etc.). The size and complexities of proteome is much larger than genome because of phenomenon like alternative splicing and post-translational modifications.

Proteome research is essentially focused on two major areas:

•  Expression proteomics:Study of up-regulation and down-regulation of protein levels

•  Functional proteomics: Study of protein activities/functions, characterization of multi-protein complexes, and role of proteins in signalling pathways.

With increase in the number of genome sequencing projects, there is a concomitant exponential growth in the number of protein sequences whose function is still unknown. The functional proteomics approaches are used to study biological functions of unknown proteins at the molecular level. In cells, many proteins display their biological functions in network (protein-protein interaction) as protein complexes. Functional proteomics is also involved in unravelling such protein-protein interactions and function of protein complexes. We have already studied methodologies used in functional proteomics during earlier lectures of the course. For example:

  •  Protein identification by mass spectrometry methodologies. Once protein is identified, function of the protein may be predicted (explained in detail during lecture 17)

..•  Methods for Protein- Protein Interaction studies are already explained in lecture 20.