PROBLEM TO BE SOLVED: To obtain the subject new protein, comprising a precursor protein of an amyloid plaque core(APC) polypeptide having a specific amino acid sequence and a protein having a function equal to that thereof, specifically present in a brain of a patient suffering from Alzheimer disease and useful for the diagnosis, etc., thereof. SOLUTION: This precursor protein of a new APC polypeptide comprises a sequence represented by the formula and further a protein has a function equal to that of the precursor protein in which at least one amino acid in the sequence is substituted or converted into a derivative. Both the proteins are capable of diagnosing Alzheimer disease at a molecular level and is useful for presymptomatic diagnosis, etc., of the Alzheimer disease. The precursor protein is obtained by extracting an mRNA from a human fetal cerebral cortex, constructing a c-DNA bank with the extracted mRNA, screening the c-DNA bank with a DNA probe having a sequence induced from a sequence of the APC protein and providing the precursor protein in which genetic information is designated with the resultant DNA using the DNA.
PRECURSOR PROTEIN OF APC POLYPEPTIDE AND ITS DIAGNOSTIC USE