Question

Beta-amyloid peptides are formed when _______________ cut the ______________.

A. apolipoprotein E ; presenilin protein

B. alpha secretase and gamma secretase ; presenilin protein

C. beta secretase and gamma secretase ; amyloid precursor protein

D. alpha secretase and gamma secretase ; amyloid precursor protein

Answer 1

$\beta$-amyloid or Amyloid $\beta$ (A$\beta$) is a peptide of 36-43 amino acids that is involved in Alzheimer's disease. It is the main components of amyloid plaques that is found in the brains of Alzheimer's patients. The peptide is resulted from the amyloid precursor protein (APP) which is cleaved by $\beta$-secretase and $\gamma$ -secretase to yield A$\beta$.

$\beta$-secretase + APP + $\gamma$ -secretase ---> A$\beta$.

SAPPa SAPPB APP AB p3 p-secrease a-secretase γ-secretase IV-secretase CTF99

Beta-amyloid peptides are formed when $\beta$-secretase and $\gamma$ -secretase cut the amyloid precursor protein (APP). (C) is the right answer.