Week 7 Exb110 2010 UPDATED

Week 7 Exb110 2010 UPDATED - Protein Degradation Continued...

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Unformatted text preview: Protein Degradation Continued EXB 110 Protein Degradation Cellular Protein Content = Synthesis rate Degradation rate Protein Degradation Other systems involved Lysosome Calpain Protein Degradation Calpain System Calcium activated proteinases in cytosol. Two major forms in muscle- calpain I ( mu-calpain) and calpain II (m-calpain). Protein Degradation Interleukin-1 (IL-1) is a proinflammatory cytokine Protein Degradation Irregular calpain activation is associated with muscular dystrophy, diabetes, multiple sclerosis and some types of cancers. Calpains are activated by the rise in calcium with exercise and are in part responsible for initiating the increase in protein degradation associated with exercise. Protein Degradation Protein Degradation evere exercise stress (causes muscle soreness and uscle damage at the microscopic level) causes isturbances in calcium homeostasis and leads to ctivation of calpains. everal research publications suggest that calpain ctivation may be the first step in the response to xercise induced muscle injury. Lysosome Lysosomes are membrane-bound organelles that function as the "stomachs" of eukaryotic cells. They contain about fifty different enzymes that break down all types of biological molecules including proteins , nucleic acids, lipids , and carbohydrates . Main enzymes are called cathepsins. Lysosome Lysosome Lysosomes vary in size (0.11.2 m) and shape, but have several common features. They are surrounded by a single membrane, have an acidic interior pH level of about 5. The low pH of the lysosome is maintained by membrane proteins that pump protons (H + ions ) from the cytosol into the lysosome. the contents of the cell are doubly protected from the digestive enzymes of the lysosome. First, the enzymes are enclosed in the lysosomal membrane and second, even if the enzymes were to leak out of the lysosome, they would not be active at the neutral pH of the cytosol. Lysosomes Exercise decreases lysosomal stability. altered lysosomal enzyme activity does not appear to be a contributing influence that challenges muscle fiber homeostasis during moderately intense running. exhaustive exercise-induced release of lysosomal enzymes was studied in the rat liver (due to pH change to 6.3 and ammonia build- up). Lysosomal changes in surviving muscle fibers in close proximity to injured muscle fibers could, by autophagic degradation, provide structural elements for the regeneration of injured muscle fibers. Lysosome Lysosome A group of genetic disorders caused by defective lysosomal enzymes demonstrates the importance of lysosomes. Called lysosomal storage diseases, these disorders are characterized by the harmful accumulation of undigested substances. The accumulated materials impair or kill the affected cells, resulting in skeletal or muscular defects, mental retardation, or even death. Whole Body Protein Synthesis and Exercise Phenylalanine and urea tracer models suggest that...
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Week 7 Exb110 2010 UPDATED - Protein Degradation Continued...

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