![]() ![]() ![]() Protein folding can go wrong for three major reasons:ġ: A person might possess a mutation that changes an amino acid in the protein chain, making it difficult for a particular protein to find its preferred fold or “native” state. Why does protein folding sometimes fail?įolding allows a protein to adopt a functional shape, but it is a complex process that sometimes fails. To draw an analogy, all vehicles are made from steel, but a racecar’s sleek shape wins races, while a bus, dump truck, crane, or zamboni are each shaped to perform their own unique tasks. By folding into distinct shapes, proteins can perform very different roles despite being composed of the same basic building blocks. Other proteins form shapes with pockets called “active sites” that are perfectly shaped to bind to a particular molecule, like a lock and key. The “snakes in a can” protein, when embedded in a cell membrane, creates a tunnel that allows traffic into and out of cells. These complex structures allow proteins to perform their diverse jobs in the cell. A few other protein structures with descriptive names include the “beta barrel,” the “beta propeller,” the “alpha/beta horseshoe,” and the “jelly-roll fold.” The tube is short and squat such that the overall structure resembles snakes (alpha helices) emerging from a can (beta sheet tube). For example, in one protein structure, several beta sheets wrap around themselves to form a hollow tube with a few alpha helices jutting out from one end. These two structures can interact to form more complex structures. Some regions of the protein chain coil up into slinky-like formations called “alpha helices,” while other regions fold into zigzag patterns called “beta sheets,” which resemble the folds of a paper fan. When folding, two types of structures usually form first. There are 22 different types of amino acids, and their ordering determines how the protein chain will fold upon itself. Proteins fold into a functional shapeĪ protein starts off in the cell as a long chain of, on average, 300 building blocks called amino acids. This wealth of diversity and specificity in function is made possible by a seemingly simple property of proteins: they fold. Others bind to specific molecules and shuttle them to new locations, and still others catalyze reactions that allow cells to divide and grow. Some are structural, lending stiffness and rigidity to muscle cells or long thin neurons, for example. Why so many? Proteins are the workhorses of the cell. There are 20,000 to over 100,000 unique types of proteins within a typical human cell. Protein formation is an error-prone process, and mistakes along the way have been linked to a number of human diseases. Current research suggests that the world of proteins is far from pristine. This work has shown that the world of proteins is a fascinating one, full of molecules with such intricate shapes and precise functions that they seem almost fanciful.Ī protein’s function depends on its shape, and when protein formation goes awry, the resulting misshapen proteins cause problems that range from bad, when proteins neglect their important work, to ugly, when they form a sticky, clumpy mess inside of cells. With the Human Genome Project complete, scientists are turning their attention to the human “proteome,” the catalog of all human proteins. We often think of proteins as nutrients in the food we eat or the main component of muscles, but proteins are also microscopic molecules inside of cells that perform diverse and vital jobs. ![]()
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