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

A rapid, easy-to-use DNA amplification method at 37 Celcius

Scientists in Japan have developed a way of amplifying DNA on a scale suitable for use in the emerging fields of DNA-based computing and molecular robotics. By enabling highly sensitive nucleic acid detection, their method ...

A microscopic topographic map of cellular function

The flow of traffic through our nation's highways and byways is meticulously mapped and studied, but less is known about how materials in cells travel. Now, a team of researchers at the University of Missouri is challenging ...

Nuclear pore complex outer rings: No longer 'one size fits all'

In eukaryotic cells, the nucleus is walled off from the rest of the cell by the nuclear envelope. All transport into and out of the nucleus occurs via cylindrical channels called nuclear pore complexes (NPCs) that penetrate ...

How the cell protects itself

The cell contains transcripts of genetic material, which migrate from the cell nucleus to another part of the cell. This movement protects the genetic transcripts from the recruitment of "spliceosomes." If this protection ...

Hybrid nanostructure steps up light-harvesting efficiency

To absorb incoming sunlight, plants and certain kinds of bacteria rely on a light-harvesting protein complex containing molecules called chromophores. This complex funnels solar energy to the photosynthetic reaction center, ...

Lab-grown dairy: The next food frontier

Lab-grown meat is getting a lot of attention along with plant-based meat substitutes. Technology is driving the industry toward providing alternatives to conventionally produced food products. Dairy proteins may be the next ...

The deep learning dive: how cells regulate division

Combining tissue imaging and artificial intelligence, Hollings Cancer Center researchers at the Medical University of South Carolina probed deeper into how cell division cycles are regulated, in this study released online ...

Translation of genes more complex than expected

Researchers from Marvin Tanenbaum's group at the Hubrecht Institute have shown that translation of the genetic information stored in our DNA is much more complex than previously thought. This discovery was made by developing ...

'Fishing a line' coupled with clockwork for daily rhythm

Organisms on this planet, including human beings, exhibit a biological rhythm that repeats about every 24 hours to adapt to the daily environmental alteration caused by the rotation of the earth. This circadian rhythm is ...

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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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