Back to Search
Start Over
Identification of the second cluster of ligand-binding repeats in megalin as a site for receptor–ligand interactions
- Source :
- Proceedings of the National Academy of Sciences. 94:2368-2373
- Publication Year :
- 1997
- Publisher :
- Proceedings of the National Academy of Sciences, 1997.
-
Abstract
- Megalin is a large cell surface receptor that mediates the binding and internalization of a number of structurally and functionally distinct ligands from the lipoprotein and protease:protease inhibitor families. To begin to address how megalin is able to bind ligands with unique structurally properties, we have mapped a binding site for apolipoprotein E (apoE)-β very low density lipoprotein (βVLDL), lipoprotein lipase, aprotinin, lactoferrin, and the receptor-associated protein (RAP) within the primary sequence of the receptor. RAP is known to inhibit the binding of all ligands to megalin. We identified a ligand-binding site on megalin by raising mAb against purified megalin, selected for a mAb whose binding to megalin is inhibited by RAP, and mapped the epitope for this mAb. mAb AC10 inhibited the binding of apoE-βVLDL, lipoprotein lipase, aprotinin, and lactoferrin to megalin in a concentration-dependent manner. When cDNA fragments encoding the four cysteine-rich ligand-binding repeats in megalin were expressed in a baculovirus system and immunoblotted with AC10, it recognized only the second cluster of ligand-binding repeats. The location of the epitope recognized by mAb AC10 within this domain was pinpointed to amino acids 1111–1210. From these studies we conclude that the binding of apoE-βVLDL, lactoferrin, aprotinin, lipoprotein lipase, and RAP to megalin is either competitively or sterically inhibited by mAb AC10 suggesting that these ligands bind to the same or closely overlapping sites within the second cluster of ligand-binding repeats.
- Subjects :
- Protein Conformation
Immunoblotting
Heymann Nephritis Antigenic Complex
Kidney
Ligands
urologic and male genital diseases
Binding, Competitive
Epitope
LDL-receptor-related protein-associated protein
medicine
Animals
Cysteine
LDL-Receptor Related Protein-Associated Protein
Binding site
Glycoproteins
Lipoprotein lipase
Binding Sites
Membrane Glycoproteins
Multidisciplinary
Microvilli
biology
Chemistry
Antibodies, Monoclonal
Biological Sciences
Ligand (biochemistry)
LRP2
Protease inhibitor (biology)
Rats
Models, Structural
Kinetics
A-site
Receptors, LDL
Biochemistry
biology.protein
Carrier Proteins
medicine.drug
Subjects
Details
- ISSN :
- 10916490 and 00278424
- Volume :
- 94
- Database :
- OpenAIRE
- Journal :
- Proceedings of the National Academy of Sciences
- Accession number :
- edsair.doi.dedup.....a750a66f9de1e46e4f593faf5b30ed7b
- Full Text :
- https://doi.org/10.1073/pnas.94.6.2368