Proteomics studies the structure and function of proteins, the principal constituents of the protoplasm of all cells.
What is a proteome?
The word “proteome” is derived from PROTEins expressed by a genOME, and it refers to all the proteins produced by an organism, much like the genome is the entire set of genes. The human body may contain more than 2 million different proteins, each having different functions. As the main components of the physiological pathways of the cells, proteins serve vital functions in the body such as:
- catalyzing various biochemical reactions, e.g. enzymes;
- acting as messengers, e.g. neurotransmitters;
- acting as control elements that regulate cell reproduction;
- influencing growth and development of various tissues, e.g. trophic factors;
- transporting oxygen in the blood, e.g. hemoglobin; and
- defending the body against disease, e.g. antibodies.
Proteins are fairly large molecules made up of strings of amino acids linked like a chain. While there are only 20 amino acids, they combine in different ways to form tens of thousands of proteins, each with a unique, genetically defined sequence that determines the protein’s specific shape and function. In addition, each protein can undergo a variety of post-translational modifications that further influence its shape and function. Researchers and scientists are working on developing a map of the human proteome – much like that of the human genome – that identifies novel protein families, protein interactions and signaling pathways.
How can proteomics be applied to medicine?
Proteomic technologies will play an important role in drug discovery, diagnostics and molecular medicine because is the link between genes, proteins and disease. As researchers study defective proteins that cause particular diseases, their findings will help develop new drugs that either alter the shape of a defective protein or mimic a missing one.
Already, many of the best-selling drugs today either act by targeting proteins or are proteins themselves. Advances in proteomics may help scientists eventually create medications that are “personalized” for different individuals to be more effective and have fewer side effects. Current research is looking at protein families linked to diseases including cancer, diabetes and heart disease.
Identifying unique patterns of protein expression, or biomarkers, associated with specific diseases is one of the most promising areas of clinical proteomics. One of the first biomarkers used in disease diagnosis was prostate-specific antigen (PSA). Today, serum PSA levels are commonly used in diagnosing prostate cancer in men. Unfortunately, many single protein biomarkers have proven to be unreliable. Researchers are now developing diagnostic tests that simultaneously analyze the expression of multiple proteins in hopes of improving the specificity and sensitivity of these types of assays.
The following links are references to studies exploring the use of proteomics in medicine:
Clinical proteomics: translating benchside promise into bedside reality
Petricoin EF, Zoon KC, Kohn EC, Barrett JC, Liotta LA
Nat Rev Drug Discov 2002 Sep;1(9):683-95
Proteomic analysis of post-translational modifications
Mann M, Jensen ON
Nat Biotechnol 2003 Mar;21(3):255-61
Early detection: Proteomic applications for the early detection of cancer
Wulfkuhle JD, Liotta LA, Petricoin EF
Nat Rev Cancer 2003 Apr;3(4):267-75
Proteomics in neuroscience: from protein to network
Grant SG, Blackstock WP
J Neurosci 2001 Nov 1;21(21):8315-8
What is the difference between proteomics and genomics?
Unlike the genome, which is relatively static, the proteome changes constantly in response to tens of thousands of intra- and extracellular environmental signals. The proteome varies with health or disease, the nature of each tissue, the stage of cell development, and effects of drug treatments. As such, the proteome often is defined as “the proteins present in one sample (tissue, organism, cell culture) at a certain point in time.”
In many ways, proteomics runs parallel to genomics: Genomics starts with the gene and makes inferences about its products (proteins), whereas proteomics begins with the functionally modified protein and works back to the gene responsible for its production.
The sequencing of the human genome has increased interest in proteomics because while DNA sequence information provides a static snapshot of the various ways in which the cell might use its proteins, the life of the cell is a dynamic process. This new data set holds great new promise for proteomic applications in science, medicine, and most notably – pharmaceuticals.
U.S. Department of Energy Office of Science, Office of Biological and Environmental Research, Human Genome Program