Measuring Nucleotide Binding to Intact, Functional Membrane Proteins in Real Time.

We have developed a method to measure binding of adenine nucleotides to intact, functional transmembrane receptors in a cellular or membrane environment. This method combines expression of proteins tagged with the fluorescent non-canonical amino acid ANAP, and FRET between ANAP and fluorescent (trinitrophenyl) nucleotide derivatives. We present examples of nucleotide binding to ANAP-tagged KATP ion channels measured in unroofed plasma membranes and excised, inside-out membrane patches under voltage clamp. The latter allows for simultaneous measurements of ligand binding and channel current, a direct readout of protein function. Data treatment and analysis are discussed extensively, along with potential pitfalls and artefacts. This method provides rich mechanistic insights into the ligand-dependent gating of KATP channels and can readily be adapted to the study of other nucleotide-regulated proteins or any receptor for which a suitable fluorescent ligand can be identified.

Citation

Samuel G Usher, Frances M Ashcroft, Michael C Puljung. Measuring Nucleotide Binding to Intact, Functional Membrane Proteins in Real Time. Journal of visualized experiments : JoVE. 2021 Mar 11(169)

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PMID: 33779593

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