# Mechanisms of Protein Self-Assembly Coupled to Membrane Mechanics in the Cell.

> **NIH NIH R35** · JOHNS HOPKINS UNIVERSITY · 2020 · $401,725

## Abstract

Project Summary: Clathrin-mediated endocytosis (CME) is an essential pathway used by all
eukaryotes for the transport of extracellular cargo into the cell. By controlling many of the signals
that are transmitted between cells, CME is a key component in the development of organisms.
Although the basic mechanism of clathrin-coated vesicle formation is known, an outstanding
question remains, how is the transition from early clathrin coated structures to productive vesicles
controlled? Productive vesicles are only produced from early structures about half of the time.
Establishing the mechanisms whereby clathrin-coat remodeling can drive disassembly or vesicle
formation is critical to understanding when cargo is internalized in healthy or diseased cells. The
problem is a natural target for biophysical modeling because the fundamental structure of the
problem (the clathrin cage) is known, but predicting how cargo uptake depends on the
stoichiometry of the components, membrane bending, or ATP-expenditure is remarkably difficult
because of the complexity of the process. We synthesize experimental data into a global model of
CME that includes the full network of interacting components and tracks the spatial and temporal
dynamics of each molecule as they diffuse, react, and assemble. In collaboration with expert cell
biologists, our computational model will provide a quantitative and visual record of clathrin-
coated vesicle formation. Our proposed work will determine physical requirements for
disassembling clathrin-coated structures on membranes, and the coupling of membrane bending
dynamics to clathrin-coated structure assembly with varying adaptor protein composition.
Through construction of a comprehensive model of CME components, we test whether the
activity of phosphatases in altering lipid composition at sites of clathrin-coated structures can
trigger selective disassembly of sites lacking cargo. This proposed work will help determine the
physical requirements for vesicle formation at fast (~ms) or slow (~seconds) time-scales, in
distinct cell types. The impact of this proposal will be a validated, `whole-cell' type model of
CME and powerful new software tools that will be publicly available for shared use. The software
will be applicable to studying mechanisms of mutli-protein assembly and membrane remodeling
not only in CME, but a wide range of cellular processes including cell division, cytoskeletal
assembly, and viral budding.

## Key facts

- **NIH application ID:** 9993555
- **Project number:** 5R35GM133644-02
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Margaret Ellen Johnson
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $401,725
- **Award type:** 5
- **Project period:** 2019-08-09 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9993555

## Citation

> US National Institutes of Health, RePORTER application 9993555, Mechanisms of Protein Self-Assembly Coupled to Membrane Mechanics in the Cell. (5R35GM133644-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9993555. Licensed CC0.

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