TY - JOUR
T1 - Dissection of receptor folding and ligand-binding property with functional minireceptors of LDL receptor-related protein
AU - Obermoeller-McCormick, Lynn M.
AU - Li, Yonghe
AU - Osaka, Hiroshi
AU - FitzGerald, David J.
AU - Schwartz, Alan L.
AU - Bu, Guojun
PY - 2001
Y1 - 2001
N2 - The LDL receptor-related protein (LRP) is a large, multifunctional endocytic receptor that binds and endocytoses a variety of structurally and functionally distinct ligands. LRP contains four putative ligand-binding domains. However, only domains II, III and IV, but not domain I, bind the receptor-associated protein (RAP), a molecular chaperone and universal antagonist for LRP. In order to dissect the function of RAP in LRP folding and to examine the ligand-binding properties of LRP, we generated LRP minireceptors that represent each of the four putative ligand-binding domains (termed mLRP1, mLRP2, mLRP3 and mLRP4, respectively). We found that proper folding and trafficking of mLRP2, mLRP3, mLRP4, but not mLRP1, is facilitated by coexpression of RAP. When these mLRPs were stably expressed in Chinese Hamster Ovary cells that lack the endogenous LRP, we found that each of these receptors was processed and traffics through the secretory pathway. Cell surface expression of these minireceptors was quantitatively examined by flow cytometric analyses. Using these minireceptor cell lines to map the ligand-binding domains, we found that although the majority of LRP ligands bind to both domain II and domain IV, Pseudomonas exotoxin A utilizes only domain IV for its binding to LRP. We conclude that while domains II and IV of LRP share many ligand-binding properties, each of the putative ligand-binding domains of LRP is unique in its contribution to ligand binding.
AB - The LDL receptor-related protein (LRP) is a large, multifunctional endocytic receptor that binds and endocytoses a variety of structurally and functionally distinct ligands. LRP contains four putative ligand-binding domains. However, only domains II, III and IV, but not domain I, bind the receptor-associated protein (RAP), a molecular chaperone and universal antagonist for LRP. In order to dissect the function of RAP in LRP folding and to examine the ligand-binding properties of LRP, we generated LRP minireceptors that represent each of the four putative ligand-binding domains (termed mLRP1, mLRP2, mLRP3 and mLRP4, respectively). We found that proper folding and trafficking of mLRP2, mLRP3, mLRP4, but not mLRP1, is facilitated by coexpression of RAP. When these mLRPs were stably expressed in Chinese Hamster Ovary cells that lack the endogenous LRP, we found that each of these receptors was processed and traffics through the secretory pathway. Cell surface expression of these minireceptors was quantitatively examined by flow cytometric analyses. Using these minireceptor cell lines to map the ligand-binding domains, we found that although the majority of LRP ligands bind to both domain II and domain IV, Pseudomonas exotoxin A utilizes only domain IV for its binding to LRP. We conclude that while domains II and IV of LRP share many ligand-binding properties, each of the putative ligand-binding domains of LRP is unique in its contribution to ligand binding.
KW - Endocytosis
KW - LRP
KW - Minireceptor
KW - RAP
KW - Receptor folding
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M3 - Article
C2 - 11181173
AN - SCOPUS:0035057838
SN - 0021-9533
VL - 114
SP - 899
EP - 908
JO - Journal of cell science
JF - Journal of cell science
IS - 5
ER -