Aside from its general effect in causing growth, growth hormone, somatotropin has multiple metabolic effects which includes: increases protein synthesis, increased free fatty acids in the blood, increased mobilization of fatty acids from adipose tissue, decreased rate of glucose utilization throughout the body.
Enhancement of Amino Acid Transport Through the Cell Membranes
Growth hormone directly enhances transport of at least some and perhaps most amino acids through the cell membranes to the interior of the cells. This increases the amino acid concentrations in the cells and is presumed to be at least partly responsible for the increased protein synthesis.
Enhancement of RNA Translation to Cause Protein Synthesis by Ribosomes
Even when the amino acid concentrations are not increased in the cells, growth hormone still increases RNA translation, causing proteins to be synthesized in greater amounts by the ribosomes in the cytoplasm.
Increased Nuclear Transcription of DNA to Form RNA
Over more prolonged periods (24 to 48 hours), growth hormone also stimulates the transcription of DNA in the nucleus, causing the formation of increased quantities of RNA. This promotes more protein synthesis and promotes growth if sufficient energy, amino acids, vitamins, and other requisites for growth are available. In the long run, this may be the most important function of growth hormone.
Decreased Catabolism of Protein and Amino Acids
There is a decrease in the breakdown of cell protein. A probable reason for this is that somatotropin also mobilizes large quantities of free fatty acids form the adipose tissue, and these are used to supply most of the energy for the body's cells, thus acting as a potent "protein sparer."
SUMMARY: Growth hormone, Somatotropin enhances almost all facets of amino acid uptake and protein synthesis by the cells, while at the same time reducing the breakdown of proteins.
Enhancement of Amino Acid Transport Through the Cell Membranes
Growth hormone directly enhances transport of at least some and perhaps most amino acids through the cell membranes to the interior of the cells. This increases the amino acid concentrations in the cells and is presumed to be at least partly responsible for the increased protein synthesis.
Enhancement of RNA Translation to Cause Protein Synthesis by Ribosomes
Even when the amino acid concentrations are not increased in the cells, growth hormone still increases RNA translation, causing proteins to be synthesized in greater amounts by the ribosomes in the cytoplasm.
Increased Nuclear Transcription of DNA to Form RNA
Over more prolonged periods (24 to 48 hours), growth hormone also stimulates the transcription of DNA in the nucleus, causing the formation of increased quantities of RNA. This promotes more protein synthesis and promotes growth if sufficient energy, amino acids, vitamins, and other requisites for growth are available. In the long run, this may be the most important function of growth hormone.
Decreased Catabolism of Protein and Amino Acids
There is a decrease in the breakdown of cell protein. A probable reason for this is that somatotropin also mobilizes large quantities of free fatty acids form the adipose tissue, and these are used to supply most of the energy for the body's cells, thus acting as a potent "protein sparer."
SUMMARY: Growth hormone, Somatotropin enhances almost all facets of amino acid uptake and protein synthesis by the cells, while at the same time reducing the breakdown of proteins.
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