Volume 133, Issue 12 pp. 6577-6582
Forschungsartikel

Probing Membrane Protein Association Using Concentration-Dependent Number and Brightness

Michael D. Paul

Michael D. Paul

Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD, 21218 USA

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Randall Rainwater

Randall Rainwater

Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, 21218 USA

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Yi Zuo

Yi Zuo

Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, 21218 USA

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Luo Gu

Luo Gu

Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, 21218 USA

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Prof. Kalina Hristova

Corresponding Author

Prof. Kalina Hristova

Department of Materials Science and Engineering and Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, 21218 USA

Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD, 21218 USA

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First published: 22 December 2020
Citations: 3

Abstract

We introduce concentration-dependent number and brightness (cdN&B), a fluorescence fluctuation technique that can be implemented on a standard confocal microscope and can report on the thermodynamics of membrane protein association in the native plasma membrane. It uses transient transfection to enable measurements of oligomer size as a function of receptor concentration over a broad range, yielding the association constant. We discuss artifacts in cdN&B that are concentration-dependent and can distort the oligomerization curves, and we outline procedures that can correct for them. Using cdN&B, we characterize the association of neuropilin 1 (NRP1), a protein that plays a critical role in the development of the embryonic cardiovascular and nervous systems. We show that NRP1 associates into a tetramer in a concentration-dependent manner, and we quantify the strength of the association. This work demonstrates the utility of cdN&B as a powerful tool in biophysical chemistry.

Conflict of interest

The authors declare no conflict of interest.

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