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Palmitoylation-defective asialoglycoprotein receptors are normal in their cellular distribution and ability to bind ligand, but are defective in ligand uptake and degradation
- Source :
-
Biochemical & Biophysical Research Communications . Oct2002, Vol. 297 Issue 4, p980. 7p. - Publication Year :
- 2002
-
Abstract
- The hepatic asialoglycoprotein receptor (ASGP-R) is an endocytic recycling receptor that mediates the endocytosis of desialylated glycoproteins. The human ASGP-R is composed of two homologous subunits, H1 and H2, and the cytoplasmic Cys residues in both subunits are palmitoylated. To study the effects of palmitoylation on ASGP-R activity and function, we generated four types of stably transfected cell lines in SK-Hep-1 hepatoma cells, expressing wild-type, or partially or completely palmitoylation-defective ASGP-Rs containing Cys-to-Ser mutations in either one or both subunits. Scatchard analysis showed that all four stable cell lines expressed a similar number of binding sites for asialo-orosomucoid, with comparable dissociation constants of ∼1–3 nM. Immunofluorescence confocal microscopy indicated a normal distribution of the palmitoylation-defective H1 and H2 subunits compared to the wild-type. However, cell lines expressing palmitoylation-defective ASGP-Rs had markedly reduced rates of ligand uptake and degradation compared to cells expressing wild-type ASGP-Rs. We conclude that failure to palmitoylate Cys residues in either or both subunits of human ASGP-Rs results in very inefficient uptake and degradation of ligands. [Copyright &y& Elsevier]
- Subjects :
- *GLYCOPROTEINS
*ENDOCYTOSIS
*LIGAND binding (Biochemistry)
Subjects
Details
- Language :
- English
- ISSN :
- 0006291X
- Volume :
- 297
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Biochemical & Biophysical Research Communications
- Publication Type :
- Academic Journal
- Accession number :
- 8516720
- Full Text :
- https://doi.org/10.1016/S0006-291X(02)02298-2