Characterization of heparan sulfate proteoglycan receptor from a permanent rat liver cell line
Guo, Yuchuan
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https://hdl.handle.net/2142/19575
Description
Title
Characterization of heparan sulfate proteoglycan receptor from a permanent rat liver cell line
Author(s)
Guo, Yuchuan
Issue Date
1990
Doctoral Committee Chair(s)
Shapiro, David J.
Department of Study
Biochemistry
Discipline
Biochemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Biochemistry
Language
eng
Abstract
The present work was undertaken to demonstrate the existence of a heparan sulfate proteoglycan (HSPG) specific receptor on the cell surface of rat liver cell (RLC), and to characterize the specificity of the ligand-receptor interaction, the properties of the receptor, and the importance of the receptor in HSPG metabolism.
The studies of the kinetics and the equilibrium of HSPG binding indicate that the binding of $\sp{35}$SO$\sb4$-HSPG by RLC is reversible, time dependent, and saturable. Two binding sites were identified by a Scatchard plot of the binding data. The specificity of the binding was elucidated by competition studies with three groups of the potential antagonists. The binding was specific for both heparan sulfate and myo-inositol phosphate derivatives but not for other types of glycosaminoglycans and polyanionic molecules, nor for other extracellular matrix glycoproteins. The receptors were soluble in nonionic detergent, SDS denaturable, sensitive to high concentrations of salt, and sensitive to protease, suggesting that the HSPG receptors (HSPGR) may be integral proteins in the cell membrane.
The kinetics of internalization and dissociation of ligand-receptor complexes were studied by following the turnover of the cell surface-bound $\sp{35}$SO$\sb4$-HSPG by RLC. It was demonstrated that it was the bound $\sp{35}$SO$\sb4$-HSPG that was endocytosed into an intracellular location, and that the HSPG was processed to oligosaccharides as it was internalized. This results provided additional evidence to support the proposed role of HSPGR in the metabolism of HSPG by RLC.
A panel of mouse monoclonal antibodies (mAbs), elicited by RLC with the exposed receptors, were isolated and used to characterize the receptor. The mAbs, both IgM and IgG, reduce the binding of $\sp{35}$SO$\sb4$-HSPG by RLC, to 20%-70% of the control. Two plasma membrane proteins with molecular weights of 90-95 kDa and 21-25 kDa reacted with mAbs. It is suggested that this membrane-bound protein might be a member of FGF family that occurs on the cell surface, and that is mediated through its associate with HSPG, and that it plays some role in the cell growth regulation. (Abstract shortened with permission of author.)
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