Protein turnover
Encyclopedia
Protein turnover is the balance between protein synthesis and protein degradation
. More synthesis than breakdown indicates an anabolic state that builds lean tissues, more breakdown than synthesis indicates a catabolic state that burns lean tissues.
Protein turnover is believed to decrease with age in all senescence
organisms including humans. This results in an increase in the amount of damaged protein within the body. It is unknown if this is a cause or consequence of aging but it seems likely that it is in fact both. The damaged protein results in a slower protein turnover which then results in more damaged protein causing an exponential increase in damage to all protein within the body and to aging.
Some bodybuilding supplement
s claim to reduce the protein breakdown by reducing or blocking the number of catabolic hormones within the body. This is believed to increase anabolism. However if protein breakdown falls too low then the body would not be able to remove muscle cells that have been damaged during workouts which would in turn prevent the growth of new muscle cells.
When older proteins are broken down in the body, they must be replaced. This concept is called protein turnover, and different types of proteins have very different turnover rates. Protein synthesis occurs during the process of translation on ribosome
s. Protein breakdown occurs generally in two cellular locations:
- Lysosomal
protease
s digest endocytosed
proteins
- Cytoplasmic
complexes, called proteasome
s, digest older or abnormal proteins that have been tagged with ubiquitin
for destruction.
Proteolysis
Proteolysis is the directed degradation of proteins by cellular enzymes called proteases or by intramolecular digestion.-Purposes:Proteolysis is used by the cell for several purposes...
. More synthesis than breakdown indicates an anabolic state that builds lean tissues, more breakdown than synthesis indicates a catabolic state that burns lean tissues.
Protein turnover is believed to decrease with age in all senescence
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...
organisms including humans. This results in an increase in the amount of damaged protein within the body. It is unknown if this is a cause or consequence of aging but it seems likely that it is in fact both. The damaged protein results in a slower protein turnover which then results in more damaged protein causing an exponential increase in damage to all protein within the body and to aging.
Some bodybuilding supplement
Bodybuilding supplement
Bodybuilding supplements are dietary supplements commonly used by those involved in bodybuilding and athletics. Bodybuilding supplements may be used to replace meals, enhance weight gain, promote weight loss or improve athletic performance...
s claim to reduce the protein breakdown by reducing or blocking the number of catabolic hormones within the body. This is believed to increase anabolism. However if protein breakdown falls too low then the body would not be able to remove muscle cells that have been damaged during workouts which would in turn prevent the growth of new muscle cells.
When older proteins are broken down in the body, they must be replaced. This concept is called protein turnover, and different types of proteins have very different turnover rates. Protein synthesis occurs during the process of translation on ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....
s. Protein breakdown occurs generally in two cellular locations:
- Lysosomal
Lysosome
thumb|350px|Schematic of typical animal cell, showing subcellular components. [[Organelle]]s: [[nucleoli]] [[cell nucleus|nucleus]] [[ribosomes]] [[vesicle |vesicle]] rough [[endoplasmic reticulum]]...
protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....
s digest endocytosed
Endocytosis
Endocytosis is a process by which cells absorb molecules by engulfing them. It is used by all cells of the body because most substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane...
proteins
- Cytoplasmic
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
complexes, called proteasome
Proteasome
Proteasomes are very large protein complexes inside all eukaryotes and archaea, and in some bacteria. In eukaryotes, they are located in the nucleus and the cytoplasm. The main function of the proteasome is to degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks...
s, digest older or abnormal proteins that have been tagged with ubiquitin
Ubiquitin
Ubiquitin is a small regulatory protein that has been found in almost all tissues of eukaryotic organisms. Among other functions, it directs protein recycling.Ubiquitin can be attached to proteins and label them for destruction...
for destruction.