Tuesday, August 17, 2010

The Sarcomere and Skeletal Muscle Disease

The gene, and its protein product, in a serious inherited muscle disease was first identified in the case of Duchenne muscular dystrophy some twenty years ago. Dystrophin turned out to be a sarcolemmal protein. This was somewhat of a surprise because many had harboured the view up until then that most muscle diseases, if not all, might be due to defects in the sarcomere itself. After all this was the site of muscle contraction. However many other muscular dystrophies have subsequently been shown to be due to defects in various other sarcolemma-associated proteins. The structure of the sarcomere itself has been studied and known for many years.2 But only in more recent times has the role of its structural and contractile proteins been detailed in specific muscle diseases. The cytoskeleton is held together by filamentous proteins, such as a-actinin and desmin, and the microtubular protein tubulin. Other proteins are nebulin and telethonin and the elastic element titin. Finally there are the contractile proteins troponin, tropomyosin, actin and myosin. Here experts in the field describe a variety of diseases

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