A recent study examined the protein synthesis in young men’s muscle and albumin after resistance exercise. The study also examined protein synthesis during rest and after resistance exercise. Branched-chain amino acids (BCAAs) were found to increase p70S6k phosphorylation. This increase in phosphorylation is important for protein metabolism in the muscle.
These changes are similar to those observed in the liver after a high-protein diet. Both the Akt and IRS1 proteins are phosphorylated by branched-chain amino acids after a meal. The Akt and IRS1 protein levels increased after the mixed meal.
Branched-chain amino acids increase p70S6k phosphorylation
Recent studies have found that branched-chain amino acids can increase p70S6k phosphorylation in muscle proteins. These amino acids mediate translational control of protein synthesis and have been shown to ameliorate muscle soreness after resistance exercise.
Branched-chain amino acids (BCAAs) are known to increase mTOR and p70S6K in muscle cells. Branched-chain amino acids have other benefits, including increased protein synthesis. Branched-chain amino acids increase AMPK activity and AMPK phosphorylation in muscle tissue.
Some studies have also suggested that the ability of leucine to activate p70S6K is involved in anabolic resistance in aging. Nevertheless, despite these findings, the relationship between MPS and chronological age has not yet been established. This is partly due to the heterogeneity of study results, which could be explained by lifestyle factors. For example, aging is associated with decreased anabolic sensitivity to food and exercise, and increased inflammation may be contributing factors.
A study done in older men indicated that BCAAs could enhance mTOR activity.
In this study, the addition of branched-chain amino acids to whey protein supplementation improved the levels of phosphorylation in MPS. It was also correlated with the amount of leucine in the muscle, a marker of the mTOR pathway.
The protein levels of mTOR, S6K1, and 4E-BP1 were determined by Western blotting. After electrophoresis, 50 mg of protein was transferred to nitrocellulose membranes. Antibodies against mTOR and S6K1 were diluted in PBS buffer containing 0.05% Tween(r)-20. The protein 단백질 보충제 bands were visualized using Image J imaging software.
Whey protein supplementation increased p70S6K phosphorylation at Thr389 in a dose-dependent manner. The phosphorylation level was 15% greater after 40 g of whey than after 30 g. This result was significant and was in line with previous MPS studies. This finding supports previous reports showing that 40 grams of whey protein increases phosphorylation of p70S6K.
Then, the phosphorylated protein intensity was normalized to total protein.
In another study, Karlsson et al. (2004) described a large magnitude shift in the mobility of total p70S6K phosphorylation. They used total ERK2 as a loading control, and compared this to the baseline sample for each group.
Exercise increases the levels of ERK1/2 and p38 MAPK, two of the major signaling pathways in muscle. However, the BCAA plus ACr group increased p70S6k phosphorylated muscles more than the BCAA alone group. Both groups showed increases in 4E-BP1 phosphorylation, though not statistically significant. However, the BCAA plus ACr supplement group increased this protein by 55%, whereas the BCAA alone group saw an increase of only 32%.
High glucose and leucine incubation suppressed the activity of a2 AMPK and mTOR in muscle. However, leucine and glucose increased malonyl CoA levels in EDL. These findings suggest that the amino acids are involved in the phosphorylation of mTOR and p70S6K.