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In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes
Published on: August 13, 2012
Conserved ectodomain cysteines are essential for rat P2X7 receptor trafficking
Marie Jindrichova1, Pavlo Kuzyk, Shuo Li
1Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Purinergic Signalling
|January 31, 2012
Summary
Disulfide bonds in the P2X7 receptor (P2X7R) are crucial for its proper cell surface expression and function. Mutating these bonds often impairs receptor trafficking, except for a specific double mutant that remains functional.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- The P2X7 receptor (P2X7R) is an ATP-gated ion channel with unique properties, including its long C-terminus, which influences its specific functions.
- Conserved cysteine residues in the ectodomain of P2X7R are suspected to form disulfide bonds critical for its structure and function.
Purpose of the Study:
- To investigate the role of conserved ectodomain cysteine residues in P2X7 receptor (P2X7R) function.
- To determine how mutations in cysteine pairs affect P2X7R expression, trafficking, and channel activity.
Main Methods:
- Site-directed mutagenesis was used to create single and double point mutants of conserved cysteine pairs in the P2X7R ectodomain.
- HEK293 cells expressing these mutants were analyzed using whole-cell current recording and biotinylation assays to assess cell-surface expression.
Main Results:
- Most cysteine pair mutants exhibited significantly reduced or non-functional currents, primarily due to decreased cell-surface expression.
- Co-expression of double mutants with wild-type P2X7R impaired receptor trafficking.
- The C119T-P2X7R double mutant showed normal plasma membrane expression and retained function, suggesting a compensatory mechanism.
Conclusions:
- All disulfide bonds within the P2X7 receptor (P2X7R) ectodomain are individually essential for proper receptor trafficking and surface expression.
- Unlike other P2X receptors, P2X7R relies on the integrity of all its ectodomain disulfide bonds for functional cell surface localization.
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