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Methods to Quantify the Dynamic Recycling of Plasma Membrane Channels
Rawad Hodeify1, Khaled Machaca2,3
1Biotechnology Department, School of Arts and Sciences, American University of Ras Al Khaimah, Ras Al Khaimah, United Arab Emirates.
Bio-Protocol
|September 18, 2023
Summary
This study introduces a novel method to measure Orai1 channel trafficking, detailing how endocytosis and exocytosis control calcium influx. This protocol can be adapted for other plasma membrane channels.
Area of Science:
- Cell Biology
- Molecular Physiology
- Biophysics
Background:
- Store-operated Ca2+ entry (SOCE) is a critical calcium signaling pathway.
- Orai1 channels mediate SOCE, with their plasma membrane (PM) residency regulated by trafficking.
- Orai1 cycling between intracellular compartments and the PM influences calcium influx levels.
Purpose of the Study:
- To present a robust protocol for quantifying Orai1 endocytosis and exocytosis rates.
- To enable the study of Orai1 trafficking as a regulatory mechanism for calcium influx.
- To provide an adaptable method for investigating the trafficking of other PM channels.
Main Methods:
- Utilized a dually tagged YFP-HA-Orai1 construct for cytosolic and extracellular labeling.
- Developed immunofluorescence assays using anti-HA antibodies and fluorescently labeled secondary antibodies to quantify endocytosis.
- Established a method involving antibody incubation, fixation, permeabilization, and Cy5/YFP ratio analysis to determine exocytosis rates.
Main Results:
- Successfully quantified Orai1 endocytosis by detecting internalized anti-HA antibody.
- Determined Orai1 exocytosis rates by fitting the Cy5/YFP ratio over time to a mono-exponential growth curve.
- Demonstrated the protocol's applicability in various cell lines.
Conclusions:
- Orai1 trafficking is a key regulatory mechanism controlling calcium influx.
- The presented protocols offer precise quantification of Orai1 endocytosis and exocytosis.
- The methodology is versatile and can be readily adapted to study the trafficking dynamics of other plasma membrane channels.
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