The BRI-Abeta40 transgene was generated with a mouse prion promoter upstream of a BRI-Abeta40 fusion construct, containing a cDNA sequence from human type 2 transmembrane protein (BRI or ITM2B) fused in-frame with a "wildtype APP695" cDNA sequence encoding amyloid-beta40 (Abeta40) at the furin-like cleavage site; the C-terminal 23 amino acid ABri peptide of BRI was replaced with the Abeta40 sequence. A single founder line with the highest Abeta40 plasma levels (line 1d) was donated to The Jackson Laboratory. Transgenic fusion protein expression approximates levels of endogenous mouse APP expression and is expressed in patterns characteristic of the Prnp promoter, with highest expression in cerebellar granule cells and hippocampus. Full length Abeta fusion protein is most highly expressed with processed Abeta40 peptide expressed at lower levels.