News tagged with protein

Related topics: cells , genes , cancer , cancer cells , amino acids

Leukemia like Achilles, has its own weakness

Leukemia cells from chronic myeloid leukemia patients, especially those in the advanced stage, lack the BRCA1 protein. Importantly, the protein is not present even if the patient carries the proper, unmutated ...

Mar 26, 2015
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Hunting the ion channel

The electrical impulse that powers the workings of the brain and the heart begins with charged particles passing through cellular structures known as ion channels. Using the same technique used to decode ...

Mar 24, 2015
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Stress granules ease the way for cancer metastasis

Tumors that produce more stress granules are more likely to metastasize, according to a study published in The Journal of Cell Biology. The results suggest that drugs to inhibit the formation of these struct ...

Mar 23, 2015
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Ras protein regulates circadian rhythm

Biochemists at the Ruhr-Universität Bochum have gained new insights into the generation and maintenance of circadian rhythms. They demonstrated that the Ras protein is important for setting the phase of such a circadian ...

Mar 18, 2015
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Breakthrough for leukaemia suffers

A research team has found a way to ensure people suffering from leukaemia are not subjected to chemotherapy if it is unlikely to help them.

Mar 18, 2015
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Protein

Proteins (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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