Genes encode proteins that are the functional molecules in cells. Proteins provide the building blocks for tissues, transmit messages, repair damage and carry out reactions that are essential for life. Proteins are hormones, enzymes, antibodies, signal transducers, transporters of energy and molecules, cytoskeleton and cell membranes constituents, among others.
The majority of the cells within the organism have the same genome (genes); however, because different cells having the same genome it doesn’t mean they are expressing exactly the same proteome (porteins). The differential expression of the proteome makes cells/tissues morphologically and functionally distinct and specific into the body.
“Did God create life? Ask a protein” (Thomas F Heinze)
GENES/GENOME versus PROTEINS/PROTEOME
Produced by Pedro Lali
Thomson MS Laboratory
State University of Campinas, Brazil
Why is important to study proteins? Abnormalities in protein production or function have been connected to health conditions, environment responses and many diseases. Indeed, nearly most drug targets are proteins - not genes.
There are many more proteins (up to 1 million) in a proteome than genes (about 25 thousand) in a human genome. A gene can encode for more than one protein, since the RNA (the gene messenger) can be spliced in different ways prior to be translated into proteins. Following translation, most proteins are chemically changed through post-translational modification, such as the addition of carbohydrate (sugars) and phosphate groups among hundred different possibilities. Proteins interact with each other inside the cell. Post-translational modifications and protein-protein interactions play indeed a vital role in modulating the function of many proteins. These dynamic processes are cell/tissue specific and have no description at the genomic level.
The proteome complexity is indicated by the following statement: “Even restricted to pair-wise interactions, there are tens of billions of possibilities of functionally significant proteins” (Cantor and Little, 1998).