Recombinant Human Apolipoprotein E (Apo-E) Fragment (residues 42-317) is a high-purity, stable protein designed for structural and biochemical research. This 276-amino acid fragment retains key functional characteristics of the full-length Apo-E, making it an ideal tool for studying lipid transport mechanisms, lipoprotein interactions, and receptor binding activities in vitro.

Apolipoprotein E (Apo-E), encoded by the APOE gene in humans, is a critical apolipoprotein that mediates lipid transport through association with various lipoprotein particles including chylomicrons, VLDL, IDL, and HDL. It functions as a core component in lipoprotein production, conversion, and clearance, facilitating lipid distribution between organs via plasma and interstitial fluids. Apo-E interacts with multiple cellular receptors including LDLR, LRP1, LRP2, LRP8, and VLDLR, enabling cellular uptake of lipoprotein particles. The protein also exhibits heparin-binding activity, supporting capture by cell surface heparan-sulfate proteoglycans. Beyond its central role in systemic lipid homeostasis, Apo-E participates in reverse cholesterol transport through HDL biogenesis and clearance, contributes to lipid transport in the central nervous system, and is involved in immune responses. The protein is primarily secreted and associates with lipoprotein particles in plasma, with lipid-poor oligomeric forms binding to extracellular matrix components in a calcium- and heparan-sulfate-dependent manner.