Human LRP-1B Antibody

LRP-1B (Low density lipoprotein-related protein #1B; also LRP-DIT) is a 600-620 kDa member of the LDLR family of proteins. It is expressed on vascular smooth muscle cells and likely neurons, and binds multiple molecules, including uPA, PAI-1, PDGFR beta uPAR, and Pseudomonas exotoxin. It is considered a tumor suppressor, and appears to block the generation of plasmin. Mature human LRP-1B is a 4579 amino acid (aa) type I transmembrane (TM) glycoprotein. It contains a 4424 aa extracellular domain (ECD) (aa 21-4444) plus a 132 aa cytoplasmic region (aa 4468-4599). In the ECD, there are 32 LDLR class A repeats, 14 EGF-like repeats, and 36 LDLR class B repeats that show an interspersing pattern. In the cytoplasmic region, one NLS (aa 4468-4474) and two endocytosis signal motifs (aa 4492-4562) are found. LRP-B1 is cleaved in the Golgi by furin after Arg3957 to create a noncovalent heterodimer consisting of a 515 kDa ECD, and an 85-95 kDa TM segment. Either uncleaved LRP-1B, or the dissociated heterodimer can undergo additional processing, leading to cleavage of the 90 kDa TM segment after Lys4435. This creates a 21 kDa TM C-terminal fragment that can undergo further gamma-secretase processing to generate a cytoplasmic, 18 kDa peptide that translocates to the nucleus. Over aa 21-244, human LRP-1B shares 81% aa identity with mouse LRP-1B.