The LDL receptor and LRP are receptors for βVLDL on pigeon monocyte-derived macrophages
- Cite this article as:
- Jones, N.L., Gupta, M. & Lewis, J.C. Vichows Archiv A Pathol Anat (1995) 426: 189. doi:10.1007/BF00192641
- 28 Downloads
Receptors for the lipoprotein, beta very low density lipoprotein (βVLDL), have been identified through the binding of βVLDL-gold conjugates on two ligand-induced regions of pigeon monocyte-derived macrophages. These regions were microvilli/retraction fibers and membrane ruffles. The present study investigated the location and identity of βVLDL receptors using an antiserum directed against the epidermal growth factor (EGF) precursor region of the human low density lipoprotein (LDL) receptor. The anti-receptor serum recognized two membrane proteins from pigeon monocyte-derived macrophages, a 116 kDa (LDL receptor) protein and a 600 kDa (low density lipoprotein receptor-related protein; LRP) protein. Ligand blot analysis demonstrated that pigeon βVLDL bound to both the LDL receptor and LRP. Immuno-gold electron microscopy using the anti-receptor serum resulted in immunoglobulin localization on the same two ligand-induced regions, microvilli/retraction fibers and membrane ruffles, to which the ligand had bound. Furthermore, simultaneous immunogold localization of the lipoprotein receptor antigens and βVLDL-gold (ligand) binding substantiated co-localization of the receptor antigens and βVLDL on the ligand-induced regions. Cross-competition studies with the anti-receptor serum and βVLDL-gold conjugates documented that increasing concentration of the anti-receptor serum resulted in 70% inhibition of βVLDL-gold conjugate binding. These data suggest that pigeon monocyte-derived macrophages utilize both the LDL receptor and LRP as receptors for pigeon βVLDL.