Proteins are the building blocks of tissue and muscles are constructed through the synthesis of protein. Human bodies produce protein from diet at a high rate during adolescence but this process slows significantly as we age. Consequently, adult muscle growth is significantly less than that of healthy teenagers. However, there are several factors that can increase muscle protein synthesis in the body.
mRNAs encoding tropomyosins
Several factors may be involved in the organization of the mRNAs encoding troposins in muscle protein. One factor, called the alpha-tropomyosin gene, is responsible for the production of both smooth and striated muscle tropomyosin isoforms. These genes encode six different mRNAs.
Mutations in the mRNAs encoding tropomechanins may result in muscle disease. One possible mechanism is that a protein may be inefficient in integrating into a sarcomere. This may result in the insertion of a non-functional protein, which disrupts myofibrillar organization.
In addition, alternative splicing can affect the expression of a protein. This is the mechanism that generates different sarcomeres and controls the functional diversity of contractile proteins. Two examples of contractile proteins that undergo alternative splicing are tropomyosin (TM) and troponin (TnT). The tropomyosin gene is highly conserved and contains several alternative cassette exons. The expression of tropomyosin in various cell types results in tissue-specific splice variants.
mRNAs encoding troponins
Troponin subunit TnT regulates multiple cellular processes in striated muscle cells and is implicated in aging-associated sarcopenia, a progressive degeneration of skeletal muscle strength. Full-length TnT3 localizes to the nucleus and is associated with RNA polymerase activity.
The genes encoding troponins are found in various tissues, including heart and muscle. The mRNAs for troponin I and troponin C are expressed in cardiac, smooth and skeletal muscle. TnIc is found in cardiac muscle, while TnIs is present in skeletal muscle. The two types of troponins share a common gene locus, but their mRNAs are different in size and structure.
Several studies have suggested that troponins may have functions beyond muscle contraction. They may be implicated in the pathogenesis of cardiomyopathy and tumorigenesis. They may also play a role in DNA replication and transcription.
Posttranslational 단백질 보충제 modifications of troponins
Posttranslational modifications of troponin subunits are known to influence cardiomyocyte contraction and function in health and disease. Recently, novel reports of troponin S-nitrosylation, O-GlcNAcylation, and citrullination have emerged. These modifications are important in cardiac diseases and may provide new therapeutic targets for cardiomyocyte relaxation defects.
These changes affect cardiac contraction and function, and are important in ischemic reperfusion. Moreover, they represent a novel signaling mechanism that is important for understanding the molecular basis of cardiac dysfunction in human myocardial infarction. The new findings may also provide insight into the design of new pharmacological interventions.
Posttranslational modifications of troponin-C peptides influence troponin subunit positioning and their interactions with the rest of the troponin complex. They also influence phosphorylation.
Regulation of muscle protein synthesis
Regulating muscle protein synthesis (MPS) is essential to the maintenance of muscle mass. Several factors affect the rate of MPS, including activity levels, the availability of essential nutrients, and the health of the muscle. Exercise and nutrition positively regulate MPS, while inactivity and disease affect it negatively.
Research has shown that an abundant supply of amino acids during exercise enhances muscle protein synthesis. In a study published in Am. J. Physiol., two researchers studied the latency and duration of skeletal muscle protein synthesis after continuous amino acid infusion. Furthermore, they investigated the availability of amino acids in the extracellular space.
The mTOR pathway is implicated in the regulation of muscle protein synthesis. In skeletal muscle cells cultured in vitro, serum conditioned with ex-vivo human serum regulates MPS. This effect is different in fasted and fed ex-vivo human serum.
Effects of exercise and nutrition on muscle protein
Exercise and proper nutrition contribute to the accumulation of muscle protein in the body. Combined, these two factors boost MPS and MPB levels. However, these effects are transient, lasting only several hours following exercise. If your goal is to increase your MPS, you should consider following a nutrition plan that provides the essential amino acids immediately post-exercise.
After exercise, athletes should pay special attention to the three R’s: repair damaged proteins and replenish muscle glycogen. This can be achieved by supplementing your diet with protein. Consuming protein immediately after exercise increases MPS, which stimulates hypertrophy.