Nicastrin

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Nicastrin is an integral membrane glycoprotein and a component of the gamma-secretase complex, which plays a crucial role in the intramembranous cleavage of several type I membrane proteins. Among these substrates, the most notable is the amyloid precursor protein (APP), from which the gamma-secretase complex generates beta-amyloid (Aβ) peptides. Aβ peptides are central to the pathogenesis of Alzheimer's disease, making the study of nicastrin and the gamma-secretase complex of significant interest in neurodegenerative disease research.

Function[edit | edit source]

Nicastrin serves as a critical component of the gamma-secretase complex, which also includes Presenilin, APH-1, and PEN-2. This complex is essential for the proteolytic processing of several membrane proteins, including Notch, ErbB-4, and CD44, in addition to APP. Nicastrin specifically is believed to function as a substrate receptor within the gamma-secretase complex, recognizing substrates that are to be cleaved. Its large extracellular domain is thought to be involved in the initial interaction with these substrates.

Structure[edit | edit source]

Nicastrin is characterized by a large extracellular domain, a single transmembrane domain, and a short cytoplasmic tail. The extracellular domain is glycosylated, which is important for its function and stability. The precise structure of nicastrin, as part of the gamma-secretase complex, has been elucidated through high-resolution structural studies, revealing insights into how it interacts with other components of the complex and its substrates.

Clinical Significance[edit | edit source]

Given its role in the production of Aβ peptides, nicastrin is a subject of interest in Alzheimer's disease research. Mutations in the components of the gamma-secretase complex, including nicastrin, can affect the cleavage of APP and the production of Aβ peptides, potentially influencing the risk of developing Alzheimer's disease. Furthermore, because gamma-secretase is involved in the processing of several other biologically important proteins, alterations in nicastrin function can have wide-ranging effects, potentially contributing to the pathogenesis of other diseases.

Research[edit | edit source]

Research on nicastrin and the gamma-secretase complex focuses on understanding the precise mechanisms of action, the structure-function relationship within the complex, and the development of inhibitors that could selectively reduce the production of pathogenic Aβ peptides without disrupting other essential gamma-secretase activities. Such selective inhibitors could offer a therapeutic strategy for Alzheimer's disease and possibly other conditions associated with gamma-secretase activity.


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Contributors: Prab R. Tumpati, MD