Monday, September 26, 2011

Proteins and Huntington's Disease

This article talks about the importance of protein folding and a few of the diseases that occur because of improper protein folding or a cell's protein quality control not being as strong.. Protein synthesis is essential for life, but it's not the only step. In order for proteins to function properly, they need to fold in the correct manner. One simple error in folding can lead to a completely inactive protein.

An example of this would be Huntington's Disease. Huntington's Disease (HD) is a dominantly inherited autosomal neurodegenerative disorder. It is characterized by the progressive development of mood disturbances, behavioral changes, involuntary choreiform movements, and cognitive impairments. Onset usually occurs in adulthood, and HD usually lasts 15-20 years before ending a person's life in a premature death.

What cause HD is the expansion of an unstable CAG repeat which encode glutamines close to the 5'-end of the gene for the huntingtin protein. The length of the CAG determines the phenotype of HD. The protein huntingin is found predominantly in the cytoplasm. It's function is not yet fully understood yet, but may involve cytoskeletal function or vesicle recycling. It has also been proposed that the gene may be transported to the nucleus and serve a role in the regulation of gene transcription, but this is not yet certain. The toxicity of huntingin may be caused by mutant full-length proteins or cleaved proteins. The Huntington gene is expressed in all cells but only affects a subset of neurons.

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