Related topics: cells , genes , amino acids , cancer , cancer cells
Protein
hideProteins (also known as polypeptides) are organic compounds made of amino acids arranged in a linear chain. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids, however in certain organisms the genetic code can include selenocysteine — and in certain archaea — pyrrolysine. Shortly after or even during synthesis, the residues in a protein are often chemically modified by post-translational modification, which alter the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins. Proteins can also work together to achieve a particular function, and they often associate to form stable complexes.
Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells. Many proteins are enzymes that catalyze biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. Other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. Proteins are also necessary in animals' diets, since animals cannot synthesize all the amino acids they need and must obtain essential amino acids from food. Through the process of digestion, animals break down ingested protein into free amino acids that are then used in metabolism.
Proteins were first described and named by the Swedish chemist Jöns Jakob Berzelius in 1838. However, the central role of proteins in living organisms was not fully appreciated until 1926, when James B. Sumner showed that the enzyme urease was a protein. The first protein to be sequenced was insulin, by Frederick Sanger, who won the Nobel Prize for this achievement in 1958. The first protein structures to be solved were hemoglobin and myoglobin, by Max Perutz and Sir John Cowdery Kendrew, respectively, in 1958. The three-dimensional structures of both proteins were first determined by x-ray diffraction analysis; Perutz and Kendrew shared the 1962 Nobel Prize in Chemistry for these discoveries. Proteins may be purified from other cellular components using a variety of techniques such as ultracentrifugation, precipitation, electrophoresis, and chromatography; the advent of genetic engineering has made possible a number of methods to facilitate purification. Methods commonly used to study protein structure and function include immunohistochemistry, site-directed mutagenesis, and mass spectrometry.
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News tagged with protein
Molecular chaperone keeps bacterial proteins from slow-dancing to destruction
Dec 28, 2009 |
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Just like teenagers at a prom, proteins are tended by chaperones whose job it is to prevent unwanted interactions among immature clients. And at the molecular level, just as at the high school gym level, it's a job that usually ...
One step closer to closure: Neuroscientists discovery key to spinal cord defects
Medicine & Health / Neuroscience
Dec 28, 2009 |
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Spinal cord disorders like spina bifida arise during early development when future spinal cord cells growing in a flat layer fail to roll up into a tube. In the Dec. 6 issue of Nature Cell Biology, researchers from the Jo ...
BBS proteins shown to run an export business that protects cilia
Dec 28, 2009 |
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A protein complex mutated in human disease removes excess signaling molecules to prevent them from damaging cilia, say researchers from UMass Medical School. The study will be published in the December 28 ...
Splitting fluorescent protein helps image clusters in live cells
Dec 26, 2009 |
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Half a protein is better than none, and in this case, it's way better than a whole one. A Rice University lab has discovered that dividing a particular fluorescent protein and using it as a tag is handy for analyzing the ...
Synergistic interaction enhances pathogenesis of Parkinson's disease
Dec 23, 2009 |
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Scientists have identified a synergistic interaction that disrupts normal intracellular transport mechanisms and leads to the accumulation of neuron-damaging clumps of protein associated with Parkinson's disease (PD), a neurodegenerative ...
Subtle change dramatically reduces pathogenic potential of Huntington's protein
Dec 23, 2009 |
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Scientists have identified a key molecular switch that may drive the onset of Huntington's disease (HD), an incurable neurodegenerative disorder that leads to severe disruptions in muscle coordination and cognitive function. ...
Scientists discover how the brain encodes memories at a cellular level
Dec 23, 2009 |
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Scientists at UC Santa Barbara have made a major discovery in how the brain encodes memories. The finding, published in the December 24 issue of the journal Neuron, could eventually lead to the development ...
Study shows a key protein helps control blood pressure
Dec 23, 2009 |
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University of Iowa researchers have shown that a protein channel helps nerve sensors in blood vessels keep blood pressure in check. Without the protein channel, known as ASIC2, the sensors are unable to send the brain the ...
Nut Roasting Benefits: Antioxidant levels of nuts increases after roasting
Dec 22, 2009 |
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The chemical reaction that darkens a batch of roasting peanuts also boosts the amount of antioxidants they contain, according to a new study in the journal Food Chemistry.
Understanding relationship of proteins, fatty acids could help treat diseases
Dec 22, 2009 |
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(PhysOrg.com) -- It's widely understood that eating a diet high in saturated fats increases the risk for a long list of chronic and deadly diseases, including diabetes and coronary heart disease. Understanding ...
New human reproductive hormone could lead to novel contraceptives
Dec 22, 2009 |
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(PhysOrg.com) -- Nearly 10 years after the discovery that birds make a hormone that suppresses reproduction, University of California, Berkeley, neuroscientists have established that humans make it too, opening ...
Protein link may be key to new treatment for aggressive brain tumor
Dec 22, 2009 |
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Biomedical researchers at the University of Central Florida have found a protein that could hold the key to treating one of the most common and aggressive brain tumors in adults.
New insight in nerve cell communication
Medicine & Health / Neuroscience
Dec 22, 2009 |
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Communication between nerve cells is vital for our bodies to function. Part of this communication happens through vesicles containing signalling molecules called neurotransmitters. The vesicle fuses with the ...
Team makes breakthrough demonstration of pH-regulating protein
Dec 22, 2009 |
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Researchers have identified the protein mechanism that senses bicarbonate fluctuations and adjusts blood pH levels.
What is the function of the protein CD20?
Dec 22, 2009 |
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Antibodies directed against the protein CD20, which is expressed by immune cells known as B cells, are used to treat B cell non-Hodgkin lymphoma and rheumatoid arthritis. Despite this, the function of CD20 has not been determined. ...
