Abeta42 and Abeta40: similarities and differences.

The abnormal accumulation of amyloid-beta (Abeta) peptide in the brain is one of the most important hallmarks of Alzheimer's disease. Abeta is an aggregation-prone and toxic polypeptide with 39-43 residues, derived from the amyloid precursor protein proteolysis process. According to the amyloid hypothesis, abnormal accumulation of Abeta in the brain is the primary influence driving Alzheimer's disease pathologies. Among all kinds of Abeta isoforms, Abeta40 and Abeta42 are believed to be the most important ones. Although these two kinds of Abeta differ only in two amino acid residues, recent studies show that they differ significantly in their metabolism, physiological functions, toxicities, and aggregation mechanism. In this review, we mainly summarize the similarities and differences between Abeta42 and Abeta40, recent studies on selective inhibitors as well as probes will also be mentioned.