Beta-amyloid

Beta-amyloid

Beta-amyloid (pronunciation: /ˈbeɪtə əˈmaɪlɔɪd/), also known as Aβ or Amyloid beta, is a peptide of 36–43 amino acids that is crucially involved in Alzheimer's disease as the main component of the amyloid plaques found in the brains of Alzheimer patients.

Etymology

The term "amyloid" comes from the Greek "amylon" which means starch, due to its reaction to iodine and sulfuric acid which is similar to starch. The prefix "beta" refers to the formation of the peptide.

Structure

Beta-amyloid is a major component of plaques in the brain of Alzheimer's patients. It is a fragment from a larger protein called Amyloid precursor protein (APP), a transmembrane protein that penetrates through the neuron's membrane. APP is cleaved into smaller fragments by enzymes such as Beta secretase 1 and Gamma secretase.

Function

Under normal conditions, beta-amyloid plays a role in neuron growth, survival, and post-injury repair. However, in Alzheimer's disease, an imbalance between the production and clearance of beta-amyloid results in the formation of plaques.

Role in Alzheimer's Disease

In Alzheimer's disease, beta-amyloid accumulates to form insoluble plaques. These plaques are toxic to neurons and lead to the symptoms of Alzheimer's. The exact mechanism of toxicity is not known, but it is believed to involve the formation of pore-like structures in the neuron's membrane, leading to an imbalance in ion homeostasis.

Related Terms

• Alzheimer's disease
• Amyloid precursor protein
• Beta secretase 1
• Gamma secretase
• Neuron
• Ion homeostasis

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