A homologous domain between the amyloid protein of Alzheimer's disease and the neurofilament subunits.

Polypeptide (A4), which is derived from a larger precursor membrane protein (beta APP), is an important component of brain amyloid in Alzheimer's disease. The physiological function and the processing of this precursor are largely unknown. In order to elucidate the actual role of beta APP, we searched for domain homology with other proteins. The present study reveals the presence of a highly conserved region between the amyloid precursor and the 3 neurofilament subunits. Identical amino acids are present at about 45% of the positions aligned between the 4 sequences. These observations are discussed in terms of a possible involvement of positive ions in the maturation of these proteins and are in favour the implication of aluminium in Alzheimer's disease.