The most common method to measure fractional synthesis rate of muscle protein(s) in vivo in humans is based on the constant infusion of a labeled amino acid tracer and quantifying the rate of incorporation of this tracer (i.e., precursor) into muscle protein(s) (i.e., product). While relative changes in synthesis rates for the same protein are attainable (Selbach et al., 2008), absolute rates are more difficult to evaluate.
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 ribosomes.Protein breakdown occurs generally in … (B) Protein synthesis rates s can be estimated from the dynamics of light peptide (P) accumulation within a short time interval t (in minutes) after medium change (Inset). II where (2, a) Equation 2 represents the amount of N15 remaining in the metabolic pool at any time t. The rapidity with which N15 is lost from the metabolic pool will be determined by B.

(C) Histogram of R 2 values of the linear fit for all 1,616 measured proteins.
The basal rate of myofibrillar protein synthesis (FSR, % h −1) was 0.034 ± 0.001 in the soleus, 0.031 ± 0.001 in the vastus, and 0.027 ± 0.001 in the triceps (Fig. The rate at which the amount of N15 present in the urea pool changes Basal protein synthesis rates in various musculoskeletal tissues are within the same range of skeletal muscle protein synthesis rates, with fractional muscle, tendon, bone, cartilage, ligament, menisci, fat, and synovium protein synthesis rates ranging between 0.02 and 0.13% per hour in … Examples of linear fits to the peptide accumulation curves for the proteins indicated in the legend.


1). When older proteins are broken down in the body, they must be replaced. In many animals the rate of protein synthesis is higher in slow‐twitch, oxidative than fast‐twitch, glycolytic muscles. Additionally, the precision of pulsed metabolic labeling is limited by requirement for nutrient shifts, which affect instantaneous rates of protein synthesis.