Amyloid

(noun)

Insoluble fibrous protein aggregates sharing specific structural traits. They arise from at least 18 inappropriately folded versions of proteins and polypeptides present naturally in the body. These misfolded structures alter their proper configuration such that they erroneously interact with one another or other cell components forming insoluble fibrils. They have been associated with the pathology of more than 20 serious human diseases in that, abnormal accumulation of amyloid fibrils in organs may lead to amyloidosis, and may play a role in various neurodegenerative disorders.

Related Terms

Examples of Amyloid in the following topics:

  • Alzheimer's Disease

    • In 1991, the amyloid hypothesis postulated that amyloid beta (Aβ) deposits are the fundamental cause of the disease.
    • In 2009, this theory was updated, suggesting that a close relative of the beta-amyloid protein, and not necessarily the beta-amyloid itself, may be a major culprit in the disease.
    • N-APP, a fragment of APP from the peptide's N-terminus, is adjacent to beta-amyloid and is cleaved from APP by one of the same enzymes.
    • In this model, beta-amyloid plays a complementary role, by depressing synaptic function.
    • Enzymes act on the APP (Amyloid precursor protein) and cut it into fragments of protein, one of which is called beta-amyloid and its crucial in the formation of senile plaques in AD

  • Prions

    • All known prions induce the formation of an amyloid fold, in which the protein polymerises into an aggregate consisting of tightly-packed beta sheets.
    • Amyloid aggregates are fibrils, growing at their ends, and replicating when breakage causes two growing ends to become four growing ends.
    • This problem does not arise if PrPSc exists only in aggregated forms such as amyloid, where cooperativity may act as a barrier to spontaneous conversion.

  • Neurodegenerative Disorders

    • Along with his colleagues, he examined the woman's brain following her death and reported the presence of abnormal clumps, which are now called amyloid plaques, along with tangled brain fibers called neurofibrillary tangles.
    • Amyloid plaques, neurofibrillary tangles, and an overall shrinking of brain volume are commonly seen in the brains of Alzheimer's patients.

  • Aging and the Nervous System

    • This consists principally of neuronal loss or atrophy, together with an inflammatory response to the deposition of amyloid plaques and neurofibrillary tangles.

  • Aging and the Endocrine System

    • Specifically, the protein beta-amyloid (Ab) collects in vulnerable brain regions and plays a central role in the progression of AD.

  • Cerebrospinal Fluid and Its Circulation

    • The three biomarkers are CSF amyloid beta 1-42, total CSF tau protein, and P-Tau181P.

  • Primary Immunodeficiency Diseases

    • They may involve various organs directly, as well as predisposing for long-term damage by leading to amyloid deposition.