Muscle 9 Flashcards
What is the protein balance responsive to?
Anabolic stimuli
What amount of protein is enough to maximally stimulate protein synthesis?
25g
What effect does AA infusion have?
Rapidly increases protein synthesis - but 2hr later it returns to baseline
How do essential amino acids stimulate protein synthesis?
mTORC1
What are the downstream targets of mTORC1?
4EBP1 and S6K
How does arginine stimulate protein synthesis?
mTOR dependent manner – if rapamycin is present, arginine will not be able to increase protein synthesis
Where do AAs need to be to increase protein turnover and synthesis?
Extracellular space
What does mTOR need to be active?
Translocate to a lysosome
What are some anabolic interventions?
Resistance exercise
AA intake
How does mTOR become active?
Insulin -Akt -mTOR-lysosome
What is important for leucyl tRNA?
couples leucine to tRNA - used by ribosome to build new proteins
Has GTPase activity - when activated by leucine can activate mTOR
What is SLC389A part of?
Lysosomal aa machinery that controls mTOR (responds to arginine)
Do protein supplements fix protein synthesis levels in elderly?
No - they aren’t responding to leucine so more leucine won’t fix the problem
What is changed in the elderly?
Total mTOR is reduced in elderly, more inflammatory signalling (increased NKB) and reduced response to essential AAs
Does increased CHO intake improve protein synthesis?
No
