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Boca‐dependent maturation of β‐propeller/EGF modules in low‐density lipoprotein receptor proteins
Author(s) -
Culi Joaquim,
Springer Timothy A,
Mann Richard S
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600132
Subject(s) - biology , receptor , microbiology and biotechnology , ldl receptor , propeller , lipoprotein , genetics , endocrinology , cholesterol , marine engineering , engineering
The extracellular portions of cell surface receptor proteins are often comprised of independently folding protein domains. As they are translated into the endoplasmic reticulum (ER), some of these domains require protein chaperones to assist in their folding. Members of the low‐density lipoprotein receptor (LDLR) family require the chaperone called Boca in Drosophila or its ortholog, Mesoderm development, in the mouse. All LDLRs have at least one six‐bladed β‐propeller domain, which is immediately followed by an epidermal growth factor (EGF) repeat. We show here that Boca is specifically required for the maturation of these β‐propeller/EGF modules through the secretory pathway, but is not required for other LDLR domains. Protein interaction data suggest that as LDLRs are translated into the ER, Boca binds to the β‐propeller. Subsequently, once the EGF repeat is translated, the β‐propeller/EGF module achieves a more mature state that has lower affinity for Boca. We also show that Boca‐dependent β‐propeller/EGF modules are found not only throughout the LDLR family but also in the precursor to the mammalian EGF ligand.