In muscle protein

Several processes contribute to the loss of weight loss of triacylglycerol in adipose tissue loss of protein in muscle hypermetabolism (increased energy expenditure, due to the... 

A. Myoglobin is the primary oxygen (O2) storage protein in muscle, where it binds... 

The secretion of estrogens in females and androgens in males by the adrenal cortex is controlled by ACTH. They are responsible for the development and maintenance of secondary sexual characters in both males and females. They also increase the deposition of protein in muscles and reduce the excretion of nitrogen in males. 

Considering the numerous specialized proteins in muscle it is not surprising that many rare hereditary muscle diseases are known. The most frequent and most studied of these is Duchenne muscular dystrophy. 

Mitochondrial Myopathy. A general deticiency of iron may ho implicated in mitochondrial myopathy, which is a complex disorder that affects muscular activity. It lias been suspected for a number of years that the disorder is caused hy a delect of mitochondrial-protein transport. H.H.V. Sdiarpa and a team of researchers (Royal Free Hospital. London) postulate that a deficiency of an iron-sulfur protein in muscle dehydrogenase may be the specific cause. 

Respiratory pigments similar to the vertebrate haemoglobins have also been identified in many invertebrates. These vary from small proteins with two Fe-porphyrin units to large molecules containing up to 190 Fe-porphyrin units. Myoglobin, the 02 storage protein in muscle tissue, is also a small iron-protoporphyrin protein. The crystal structures of this and a number of other porphyrin proteins are now known (Chapter 20.2, Table 11). 

Globular proteins (in enzymes) and structural proteins (in muscle) produced from amino acids... 

Blake DJ, Weir A, Newey SE, Davies KE. 2002. Function and genetics of dystrophin and dystrophin-related proteins in muscle. Physiol Rev 82 291-329. 

A protein is a biological polymer that is made up of nitrogen, carbon, hydrogen, oxygen, and sometimes other elements. Our bodies are mostly made out of proteins. For example, the most abundant protein in your body is collagen, which is found in skin and bones. Your hair has structural proteins, such as keratin, shown in Figure 5. Proteins in muscles allow your muscles to contract, making body movement possible. 

It is more advantageous for the human body to store fuel as triacylglycerol in adipose tissue than as protein in muscle because adipose triacylglycerol stores contain... 

Fi re 28-14 The amino acid sequence and the three-dimensional representation of myoglobin, the oxygen-storing protein in muscles. 

Although there may be some exceptions, it appears likely that the majority of the proteins in muscle fibers are synthesized in situ. Preparations of ribosomes can be made from muscle which are capable of synthesizing protein under conditions similar to those used for other tissues (Yl). Varying estimates have been made of the rate of turnover of muscle proteins (PIO) older estimates of protein half-lives are probably too long owing to error resulting from the reutilization of the labeled... 

It seems reasonable to suppose that the elevated cathepsin activity in dystrophic muscle, by enhancing muscle protein breakdown in vivo, is the cause of the increased rate of protein turnover the increased synthesis could then be seen as an adaptive response to the accelerated breakdown. There is yet, however, no real evidence that this is so the factors which control the breakdown of protein in muscle fibers are probably complex and little understood (PIO). A further possibility, that the proteins of atrophying muscles are in some way more susceptible to breakdown by proteolytic enzymes, seems unlikely Kohn (K9) reported that myosin from denervated rat muscle was digested normally by trypsin, and this was found to be true also of myosin from dystrophic mice and chickens (Kl), whereas Pollack and Bird (P21) stated that the autolytic activity of denervated muscle was not increased relative to the breakdown of hemoglobin by the muscle. 

Organic Compounds. Sucrose, glucose, other sugars, and sorbitol have cryoprotective effects on frozen mince of Alaska pollack (60,118) and carp actomyosin (117,119,120). Furthermore, ethylene glycol, glycerol (121,122), and citrate (123) have cryoprotective effects on the proteins in muscles of Alaska pollack and cod. 

Basically, there are three major groups of proteins in muscle tissue (a) the sarcoplasmic proteins of the muscle cell cytoplasm, (b) the myofibrillar proteins, soluble at high ionic strengths, that make up the myofibril or contractile part of the muscle, and (c) the stromal proteins comprised largely of the connective tissue proteins, collagen, and elastin. The myofibrillar proteins and the stromal proteins are fibrous and elongated they form viscous solutions with large shear resistance. These properties coupled with other lines of indirect evidence indicate that the physical properties of the myofibrillar and stromal proteins are directly related to the texture and tenderness of meat (34). 

The major proteins in muscle are actin and myosin. Actin and myosin are also found in many other kinds of cells besides muscles and are involved in several kinds of cellular and intracellular motions (e. g., cell motility and changes of cell shape). 

Fuel Stores. Any dietary fuel that exceeds the body s immediate energy needs is stored, mainly as triacylglycerol (fat) in adipose tissue, as glycogen (a carbohydrate) in muscle, liver, and other cells, and, to some extent, as protein in muscle. When we are fasting, between meals and overnight while we sleep, fuel is drawn from these stores and is oxidized to provide energy (Fig. 1.1). 

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