Each protein can be identified by its unique amino acid sequence, the three-dimensional shape of the protein (that mainly depends on amino acid sequence and other environmental factors), function of the protein, and cellular location.
The proteins expressed in a cell may be intracellular (present within the cell) or extracellular (secreted outside the cells), or circulating in the blood like hormones, immunoglobulins, etc., constantly interacting with other molecules such as proteins, lipids, sugars, DNA, RNA, metal ions, vitamins, etc., or with other cells. The functions of these circulating proteins are also influenced by their interaction with other molecules that are present nearby. Even though the total number of genes estimated is about 35,000, the actual number of proteins is much higher than this. About 17, 000 proteins were identified at the gene level but information regarding their function and biological role is still being investigated in detail.
The type and total number of genes in an organism will be stable (static) and are identical in all somatic cells of an organism. But, the total number of proteins expressed by a cell (protein profile) of an organism is always variable (dynamic). The protein profile of a cell depends on its metabolic state, stage of development, and other micro- and macro-environmental factors, which influence the expression of a set of genes at a particular time. Therefore, the challenge for the future is to determine the actual total number of proteins expressed in each cell type and find out the functions and biological role of these proteins in metabolism, health, and disease. These topics provide an exposure to the three-dimensional structure of proteins and their relationship to proteomics, recombinant DNA technology, genomics, and finally bioinformatics.
Tags: Bio Technology, Bio Genetics, Proteins
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