Conditional fast expression and function of multimeric TRPV5 channels using Shield-1

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Conditional protein expression is crucial for studying protein function.
• Existing methods have limitations in controlling protein stability and complex formation.
• The mutated FK506-binding protein-12 (mtFKBP) system offers a novel approach to protein regulation.

Purpose of the Study:

• To adapt and validate the mtFKBP system for studying multimeric plasma membrane proteins.
• To investigate the conditional expression and complex formation of the TRPV5 ion channel.
• To establish a method for analyzing protein complexes without destabilizing all subunits.

Main Methods:

• Fusion of mtFKBP to the TRPV5 ion channel.
• Application of the cell-permeant ligand Shield-1 to control mtFKBP-TRPV5 stability and expression.
• Co-expression of mtFKBP-TRPV5 with untagged TRPV5 to study heteromultimeric channel formation.
• Analysis of protein degradation upon Shield-1 washout.

Main Results:

• mtFKBP-TRPV5 fusion proteins form functional ion channels.
• TRPV5 expression is precisely controlled in a time- and dose-dependent manner by Shield-1.
• mtFKBP-TRPV5 can form heteromultimeric channels with endogenous TRPV5.
• Shield-1 withdrawal leads to co-degradation of heteromultimeric complexes, enabling their study.

Conclusions:

• The mtFKBP system provides a powerful tool for conditional expression of membrane proteins.
• This method facilitates the study of multimeric protein complexes, including heteromultimers.
• The strategy offers a novel approach to investigate protein complex dynamics and assembly in living cells.