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An X-linked NDI mutation reveals a requirement for cell surface V2R expression
H M Sadeghi1, G Innamorati, M Birnbaumer
1Department of Anesthesiology and Molecular Biology Institute, University of California Los Angeles School of Medicine, 90095, USA.
Molecular Endocrinology (Baltimore, Md.)
|June 1, 1997
Summary
The V2 vasopressin receptor (V2R) R337ter mutant is nonfunctional because it fails to reach the plasma membrane. Minimal protein length is required for V2R cell surface expression and function, suggesting endoplasmic reticulum quality control.
Area of Science:
- Molecular biology
- Cell biology
- Biochemistry
Background:
- X-linked recessive nephrogenic diabetes insipidus is caused by V2 vasopressin receptor (V2R) mutations.
- The V2R R337ter mutant, identified in patients, leads to this condition.
- Understanding V2R mutant function is crucial for disease research.
Purpose of the Study:
- To investigate the function and biochemical properties of the V2R R337ter mutant.
- To determine the minimal protein length required for V2R cell surface expression and function.
- To explore the role of protein quality control in V2R maturation.
Main Methods:
- Receptor expression in COS.M6 or HEK293 cells.
- Binding assays and adenylyl cyclase activity measurements.
- Metabolic labeling, ELISA, and endoglycosidase H treatment.
Main Results:
- The V2R R337ter mutant was synthesized but nonfunctional, failing to reach the plasma membrane.
- The mutant receptor was retained as a precursor form, with arrested maturation.
- A minimal length of four additional amino acids (V2R-341ter) was sufficient for cell surface expression and function.
Conclusions:
- The V2R R337ter mutant is nonfunctional due to its inability to reach the plasma membrane.
- Sufficient protein length is essential for V2R translocation and function.
- Evidence suggests an endoplasmic reticulum quality control mechanism independent of glycosylation.