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Contribution of cubilin and amnionless to processing and membrane targeting of cubilin-amnionless complex.
- Source :
-
Journal of the American Society of Nephrology : JASN [J Am Soc Nephrol] 2005 Aug; Vol. 16 (8), pp. 2330-7. Date of Electronic Publication: 2005 Jun 23. - Publication Year :
- 2005
-
Abstract
- Cubilin is a peripheral apical membrane receptor for multiple ligands that are taken up in several absorptive epithelia. Recently, amnionless (AMN) was identified to form a functional receptor complex with cubilin. By expression in transfected polarized MDCK cells of AMN and several cubilin fragments, including a functional "mini" version of cubilin, the processing, sorting, and membrane anchoring of the complex to the apical membrane were investigated. The results show that truncation mutants, including the N-terminal domain of cubilin, did not appear at the plasma membrane but instead were retained in the endoplasmic reticulum or partially secreted into the medium. Coexpression with AMN led to efficient transport to the apical cell surface of the cubilin constructs, which included the EGF domains, and prevented release into the medium. AMN co-precipitated with cubilin and co-localized with cubilin at the apical cell surface. Apical sorting was observed for a broad set of nonoverlapping cubilin fragments without the N-terminal region, in the absence of AMN. The preference for apical sorting disappeared when glycosylation was inhibited by tunicamycin. In conclusion, it is shown that both units contribute to the processing of the cubilin-AMN complex to the apical membrane: AMN interacts with the EGF domains of cubilin and is responsible for membrane attachment and export of the complex from the endoplasmic reticulum, whereas the extracellular cubilin molecule is responsible for apical sorting of the complex in a carbohydrate-dependent manner.
- Subjects :
- Animals
Blotting, Western
Carbohydrates chemistry
Cell Line
DNA, Complementary metabolism
Dogs
Endoplasmic Reticulum metabolism
Epidermal Growth Factor chemistry
Epidermal Growth Factor metabolism
Epithelial Cells cytology
Epithelium metabolism
Glycosylation
Green Fluorescent Proteins metabolism
Kidney cytology
Ligands
Membrane Proteins metabolism
Microscopy, Confocal
Microscopy, Fluorescence
Models, Genetic
Protein Binding
Protein Structure, Tertiary
Rats
Receptors, Cell Surface chemistry
Receptors, Cell Surface metabolism
Transfection
Cell Membrane metabolism
Membrane Proteins physiology
Receptors, Cell Surface physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1046-6673
- Volume :
- 16
- Issue :
- 8
- Database :
- MEDLINE
- Journal :
- Journal of the American Society of Nephrology : JASN
- Publication Type :
- Academic Journal
- Accession number :
- 15976000
- Full Text :
- https://doi.org/10.1681/ASN.2004110925