The A2MR-α2 monoclonal antibody specifically reacts with a 600 kDa, type I membrane single protein, also known as the α2 Macroglobulin (α2M) receptor/low density lipoprotein receptor-related protein 1 (LRP-1). Reported to be an endocytic receptor involved with intracellular signalling, lipid homeostasis, clearance of apoptotic cells, and α2 Macroglobulin mediated clearance of secreted amyloid precursor protein found in Alzheimer patients. The single chain receptor undergoes cleavage, shortly after synthesis, into the 85 kDa transmembrane β chain that non-covalently binds to the extracellular 500-515 kDa a chain. It has a broad cellular distribution, but in the hematopoietic system it is expressed on monocyte lineage cells. α2M/LRP-1 mediates endocytosis of a variety of ligands including α2M-proteinase complexes, plasminogen activators in complex with plasminogen activator inhibitor, or Pseudomonas Exotoxin A. Ligand binding to α2M/LRP-1 is followed by rapid transport of the ligand to lysosomes for degradation.