Finite Phase-separation FRET I: A quantitative model valid for bilayer nanodomains

TL;DR

This paper introduces a quantitative model based on FRET to analyze the size and distribution of nanoscopic phase domains in lipid bilayers, aiding understanding of membrane heterogeneity.

Contribution

It develops a novel domain size-dependent FRET model derived from a radial distribution function for binary hard disk fluids, improving analysis of membrane nanodomains.

Findings

The model accurately predicts domain sizes in lipid mixtures.

Comparison shows the model aligns well with existing approaches.

Provides a new tool for studying membrane phase behavior.

Abstract

Multicomponent lipid mixtures exhibit complex phase behavior, including coexistence of nanoscopic fluid phases in ternary mixtures mimicking the composition of the outer leaflet of mammalian plasma membrane. The physical mechanisms responsible for the small size of phase domains are unknown, due in part to the difficulty of determining the size and lifetime distributions of small, fleeting domains. Steady-state FRET provides information about the spatial distribution of lipid fluorophores in a membrane, and with an appropriate model can be used to determine the size of phase domains. Starting from a radial distribution function for a binary hard disk fluid, we develop a domain size-dependent model for stimulated acceptor emission. We compare the results of the model to two similar, recently published models.