# Chemically engineered bilayers for cryoEM imaging of membrane proteins in continuous membranes

> **NIH NIH R21** · HAUPTMAN-WOODWARD MEDICAL RESEARCH INST · 2020 · $291,000

## Abstract

Cells interact with their environments through membrane proteins. Structural and functional studies of
membrane proteins are thus very important. Structure determination of eukaryotic membrane proteins in
membrane however remains difficult despite substantial progresses. Part of the challenge comes from the fact
that many eukaryotic membrane proteins undergo a complicated intracellular maturation process and carry
different post-translational modifications before reaching their final destinations. Current high throughput
crystallization and cryoEM single particle reconstruction are largely carried out with proteins in detergents, or in
membrane-mimetic systems such as bicelles, nanodiscs, lipid-cubic phases or amphipols, where there are still
significant differences in comparison with a native membrane. New technologies are needed to overcome
these problems. We propose here to develop two new technologies for cryoEM study of membranes proteins
in continuous membrane using type 1 IP3 receptor (IP3R) as a working model. The premise of these two
methods is partly based on our recent work of a chemical engineering procedure that is suitable for
functionalizing nanometer-thick carbon films and of a bead-supported spherical unilamellar membrane (bSUM)
system that allows the generation of stable giant unilamellar vesicles. With milligram amounts of IP3R proteins,
we will produce a nanometer-bSUM (nm-bSUM) and a carbon-supported planar unilamellar membrane (cPUM).
These two systems will be prepared for the cryoEM visualization of the IP3Rs in continuous membrane where
the proteins are fully immersed in a lipid bilayer, and will allow us to resolve the receptor structure from images
of membrane-integrated molecules. Images of the receptors in nm-bSUMs will be used for random spherically
constrained (RSC) reconstruction. Receptors in cPUMs will be imaged at high tilt angles for 3D reconstruction
with corrections for changes in defocus levels across the imaging field. Both methods will rely on chemical
engineering and membrane reconstitution at the nanometer scale and will result in efficient unidirectional
insertion of membrane proteins at sub-nM concentrations, which will be particularly beneficial for selecting
specifically labeled mature functional membrane proteins or enriching low-abundance membrane protein
complexes at sub-nM concentrations. Results of the proposed studies will create new windows of opportunities
for cryo-EM study of various membrane protein complexes in membrane and for using nanoscale membrane
systems in other bioanalytical or biomedical applications.
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## Key facts

- **NIH application ID:** 10091731
- **Project number:** 7R21GM131231-02
- **Recipient organization:** HAUPTMAN-WOODWARD MEDICAL RESEARCH INST
- **Principal Investigator:** Aviv Paz
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $291,000
- **Award type:** 7
- **Project period:** 2019-02-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10091731

## Citation

> US National Institutes of Health, RePORTER application 10091731, Chemically engineered bilayers for cryoEM imaging of membrane proteins in continuous membranes (7R21GM131231-02). Retrieved via AI Analytics 2026-06-01 from https://api.ai-analytics.org/grant/nih/10091731. Licensed CC0.

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