Prion Protein Paralog Doppel Protein Interacts with Alpha-2-Macroglobulin: A Plausible Mechanism for Doppel-Mediated Neurodegeneration
Deposition of beta-amyloid (A beta), a metabolite of approximately 4 kd of the amyloid precursor protein, is a critical pathological feature in Alzheimer disease. We postulate that deposition reflects an imbalance of A beta synthesis and clearance. Several pathways that impact A beta converge on a single receptor molecule, the low-density lipoprotein receptor-related protein (LRP). This multifunctional receptor is the major neuronal receptor both for apolipoprotein E (apoE, protein; APOE, gene) and for alpha2-macroglobulin (alpha2M, protein; A2M, gene), and it mediates clearance of apoE/A beta and alpha2M/A beta complexes. The LRP also interacts with the amyloid precursor protein itself. In this review, we highlight data that support a role for LRP in A beta metabolism and hypothesize that LRP therefore plays a critical role in Alzheimer disease.