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A fully active nonglycosylated V2 vasopressin receptor
G Innamorati1, H Sadeghi, M Birnbaumer
1Department of Anesthesiology and Molecular Biology Institute, UCLA School of Medicine 90095, USA.
Molecular Pharmacology
|September 1, 1996
Summary
The human V2 vasopressin receptor is glycosylated but often improperly processed, leading to aggregation. However, stable expression yields mature receptors, and glycosylation is not essential for function or desensitization.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- The V2 vasopressin receptor is a G protein-coupled receptor crucial for regulating water balance.
- It possesses a potential N-linked glycosylation site on its extracellular domain.
Purpose of the Study:
- To investigate the glycosylation status and processing of the human V2 vasopressin receptor.
- To determine the functional significance of V2 receptor glycosylation.
Main Methods:
- Transient and stable transfection of cells expressing the V2 vasopressin receptor.
- Metabolic labeling, immunoprecipitation, and glycosidase treatment.
- Site-directed mutagenesis of the glycosylation site (Asn22 to Gln).
- Ligand binding assays and assessment of receptor desensitization.
Main Results:
- Transiently expressed V2 receptors were glycosylated but predominantly immature, forming aggregates.
- Stably expressed V2 receptors were predominantly mature and properly processed.
- N-glycosylation was not essential for ligand binding, coupling, or desensitization, as the nonglycosylated mutant retained wild-type characteristics.
Conclusions:
- V2 vasopressin receptor processing is dependent on the expression system, with stable expression favoring proper maturation.
- N-linked glycosylation at Asn22 is not critical for the fundamental functions of the V2 vasopressin receptor.