Deficiency of a glycoprotein component of the dystrophin complex in dystrophic muscle

Article Abstract:

Duchenne muscular dystrophy (DMD) is a disease of the muscles caused by a defective gene on the X chromosome; it affects only boys and usually results in death by age 20. Study of this defective DMD gene has revealed coding for dystrophin, an integral protein in the membrane of normal skeletal muscle fiber, but people with DMD are missing this protein. The study of other genetic diseases has revealed that when one protein is affected, others associated with it are affected also. In DMD patients, one of the four glycoproteins (carbohydrate and protein complexes) that make up the structure of this protein is deficient. It is hypothesized that the reduction of this dystrophin-associated glycoprotein may hold a clue to discovering the cause of this type of muscular dystrophy. Reduction of this glycoprotein can lead to a destabilization of the plasma membrane around the skeletal muscle cell, and the proteins associated with this membrane. This membrane destabilization can in turn lead to a deregulation of the intracellular calcium, which could cause abnormal activation of calcium-dependent protease (enzymes that breakdown proteins) activity. In DMD the muscle protein gradually degenerates, which could be explained by this proposed abnormal enzymatic activity. (Consumer Summary produced by Reliance Medical Information, Inc.

Development and progression, Glycoproteins, Muscular dystrophy

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Association of dystrophin-related protein with dystrophin-associated proteins in mdx mouse muscle

Article Abstract:

Those suffering from Duchenne muscular dystrophy share with mdx mice a lack of dystrophin, which induces a loss of dystrophin-associated proteins (DAPs) in the sarcolemma. This loss could be mitigated by the dystrophin-related protein (DRP) utrophin, which is found in the sarcolemma in cardiac and skeletal muscles of adult mdx mice. Because DRP and DAP colocalize to the neuromuscular junction, DRP could help retain DAP in the sarcolemma.

Physiological aspects, Muscle proteins, Duchenne muscular dystrophy

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Direct binding of G-protein beta gamma complex to voltage-dependent calcium channels

Article Abstract:

The control of neurotransmitter release at the synapse is significantly influenced by voltage-dependent Ca(2+) channels. Certain G-protein-coupled receptors can restrain these channels through a pathway inherent to the membrane. Evidence is presented demonstrating that channel inhibition occurs when G protein beta gamma complex and the pore-forming alpha(sub 1) subunits of several types of the channels directly interact.

Calcium channels, Protein binding, G proteins

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