Quantitative FRET FLIM imaging reveals multiple interactions between proteins of the ESYT, ORP, and VAP families at the endoplasmic reticulum membrane
Abstract
The endoplasmic reticulum (ER) is a highly dynamic intracellular organelle that forms close contact sites with other organelles and the plasma membrane. These membrane contact sites play essential roles in lipid exchange and calcium homeostasis. ER membrane proteins from the VAP, ORP, and ESYT families are key players in the formation and function of these contacts. Numerous interactions between these proteins are likely critical for their activity. We investigate the interactome between these protein families in live cells by analyzing two members from each family, using Förster Resonance Energy Transfer (FRET) between pairs of proteins labeled with fluorescent proteins (FP). FRET is detected by Fluorescence Lifetime Imaging Microscopy (FLIM). Our quantitative approach shows that all tested proteins clusterize and sometimes interact within their respective families, and that their organization at the nanometer scale can be disrupted by specific mutations or domain deletions. In particular, we show that the coiled-coil domains of ORP5 and ORP8 are required for the formation of both homomeric and heteromeric complexes. Moreover, we demonstrate that FRET-FLIM can detect intra-molecular conformational changes in response to alterations in the cellular environment, such as variations in Ca²⁺ concentration, as observed for ESYT1. We also identify novel inter-family organization, including clustering between VAPB and ORP8, and between ESYT2 and ORP5/8. Finally, our approach highlights the broad interaction network (interactome) of VAPA/B, and shows how various potential binding partners can influence FRET efficiency.
Related
- Plasma proteomics identifies an endoplasmic reticulum stress-associated molecular signature across cardiovascular-kidney-metabolic syndrome stages
- Emodin induces defensive autophagy against white spot syndrome virus infection via targeting the hemocyanin-mediated endoplasmic reticulum-mitochondrial crosstalk in shrimp
- ARID5A Is a PERK-Dependent Effector of the Endoplasmic Reticulum Stress Response That Protects Against Steatohepatitis
- Transmembrane-domain-driven heterodimer assembly licenses integrin head-domain folding in the endoplasmic reticulum
- Endoplasmic reticulum and Golgi stress signaling-mediated regulation of protein secretion
BibTeX
@article{zamiati2026quantitative,
title = {{Quantitative FRET FLIM imaging reveals multiple interactions between proteins of the ESYT, ORP, and VAP families at the endoplasmic reticulum membrane}},
author = {Dounia Zamiati and Mouna Abdesselem and Oliver Nüsse and Marie Erard},
journal = {Journal of Biological Chemistry},
year = {2026},
month = sep,
doi = {10.1016/j.jbc.2026.113144},
url = {https://hal.science/hal-05759645v1},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - JOUR
TI - Quantitative FRET FLIM imaging reveals multiple interactions between proteins of the ESYT, ORP, and VAP families at the endoplasmic reticulum membrane
AU - Dounia Zamiati
AU - Mouna Abdesselem
AU - Oliver Nüsse
AU - Marie Erard
PY - 2026
DA - 2026/09/22
JO - Journal of Biological Chemistry
DO - 10.1016/j.jbc.2026.113144
UR - https://hal.science/hal-05759645v1
AB - The endoplasmic reticulum (ER) is a highly dynamic intracellular organelle that forms close contact sites with other organelles and the plasma membrane. These membrane contact sites play essential roles in lipid exchange and calcium homeostasis. ER membrane proteins from the VAP, ORP, and ESYT families are key players in the formation and function of these contacts. Numerous interactions between these proteins are likely critical for their activity. We investigate the interactome between these protein families in live cells by analyzing two members from each family, using Förster Resonance Energy Transfer (FRET) between pairs of proteins labeled with fluorescent proteins (FP). FRET is detected by Fluorescence Lifetime Imaging Microscopy (FLIM). Our quantitative approach shows that all tested proteins clusterize and sometimes interact within their respective families, and that their organization at the nanometer scale can be disrupted by specific mutations or domain deletions. In particular, we show that the coiled-coil domains of ORP5 and ORP8 are required for the formation of both homomeric and heteromeric complexes. Moreover, we demonstrate that FRET-FLIM can detect intra-molecular conformational changes in response to alterations in the cellular environment, such as variations in Ca²⁺ concentration, as observed for ESYT1. We also identify novel inter-family organization, including clustering between VAPB and ORP8, and between ESYT2 and ORP5/8. Finally, our approach highlights the broad interaction network (interactome) of VAPA/B, and shows how various potential binding partners can influence FRET efficiency.
SN - 0021-9258
SN - 1083-351X
ER -