Nicastrin also known as NCSTN is a type I transmembrane glycoprotein that is an integral component of the multimeric gamma-secretase complex. Nicastrin plays a crucial role in the assembly and function of the presenilin complex, which is essential for the proteolytic processing of various substrates, including the β-Amyloid precursor protein (βAPP) and Notch. Nicastrin mediates the signaling pathways associated with Notch and GLP-1 and influences the production of the neurotoxic β-Amyloid peptide, a key factor in the pathogenesis of Familial Alzheimer′s disease (FAD). Nicastrin features hydrophilic amino and carboxy-terminal domains, a short hydrophobic transmembrane domain, and potential sites for post-translational modifications such as N-myristoylation and phosphorylation, which may affect stability and interactions within the presenilin complex.