A Protein for a Life Stage

Many proteins are multifunctional and serve different systems of the body via different processes. Protein variety covers the biological spectrum from the physiological, cellular, chromosomal, and neurological to the hormonal, antioxidant, metabolic, and immunological. The orchestration and integration of protein function is as complex as life itself.

In the images above, we’re looking at just a handful of specific proteins to demonstrate the macroscopic effects of microscopic protein molecules. While proteins support health all throughout your life, certain proteins have pronounced effects at specific developmental stages. LESS

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Proteins are the first members of the immune system to encounter and launch a defense against pathogens. The complement system, a subdivision of the immune system, is made up of proteins in the bloodstream that can rapidly be dispatched to a site where foreign substances are present.

The complement proteins — also known as antibodies — are the sergeants of the immune army, identifying invader locations and directing ranks of immune cells to destroy foreign substances. Antibodies can also trigger inflammation (an initial immune response to injury or insult), kill foreign cells, and/or disable foreign particles so that they’re more easily destroyed and devoured by various types of immune cells.

Protein as Builder

Like the wood used to create a building’s posts and beams, some types of proteins are structural components of the body’s bones, tissues, and fluids. They construct not only vessels, but the blood that runs through them; not only bones, but the muscle that gives movement. In the structure of certain tissues, proteins are bound together or bound with other types of molecules to form strong composites. Collagen, the most abundant protein in the body, is a fibrous composite that lends structure and strength to tendons, cartilage, bone, and teeth. Elastin, a well-named protein, is pliable: it’s used to form the ligaments between bones, which must be flexible enough to allow movement; and to form arteries, which need to expand and contract as blood flows.

Only specific proteins function as biomaterials for construction. Others are involved in the building process in entirely different roles, such as inducing cells to form tissues and sending signals to stimulate growth. LESS

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Proteins also assume important roles in energy production and usage that other nutrients do not. Transporting energy-giving sugar into cells is the job of proteins known as glucose transporters. The first to be discovered was the protein GLUT-1 (GLUcose Transporter #1). Scientists aren’t quite sure how this protein helps sugar pass into a cell, but they believe it promotes a process of diffusion by stretching its multi-helix shape over a cell membrane and creating a channel through which the glucose molecules can pass.

Protein as Mover

Behind our every movement is an extraordinary sequence of physiologic events that begins with the response to a stimulus, causing a message sent from the brain and a reply from calcium ions in the muscle, which in turn leads to muscle contraction and relaxation. But the actual mechanics of muscle movement is the work of proteins.

Muscle tissue is made up of tiny fibers all bundled together. The fibers are made up of even smaller strands of conjoined protein filaments. Thick filaments are made primarily of the protein myosin, and thin filaments of the protein actin (plus molecules of troponin and tropomyosin). Best scientists understand it, muscles contract when the thick myosin filaments slide farther inside the thin actin tubes, like the shaft of a piston sliding into its cylinder.

Myosin is referred to as a “motor protein” due to its capability to move within muscle fibers. Kinesin is another type of motor protein with the remarkable ability to “walk” along the top of microtubules — something like a kid walking along the top of a drain pipe — to deliver cellular messages. LESS

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Though catabolism is described as destructive, it’s a dynamic process that is ultimately productive and invaluable. It is in the catabolic phase of protein metabolism that the bulldozing — the smashing, moving, and rebuilding of molecules — is done.

Complete proteins within the foods you eat are broken down into their individual amino-acid building blocks during digestion and then absorbed through the intestine into the blood stream. When there are more amino acids in the blood than the body needs — commonly the case in American diets due to our overconsumption of meats — the molecules are converted to glycogen or fat. The amino acids that can be used right away continue to be catabolized.

In the breaking down, their carbon shells are converted to acetyl CoA (coenzyme A), a coenzyme that becomes oxidized and produces ATP (adenosine triphosphate). ATP is sometimes referred to as “cell fuel” since it provides the energy for cells to carry out their countless functions in your body. ATP is produced when carbohydrates and fats are digested as well — but it always takes a protein-based enzyme to complete ATP production. LESS

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