# Protein Networks as Synergistic Drivers of Membrane Traffic

> **NIH NIH R01** · UNIVERSITY OF TEXAS AT AUSTIN · 2020 · $368,897

## Abstract

PROJECT SUMMARY Assembly of trafficking vesicles plays a key role in many human diseases. More than 50
cytoplasmic proteins work together to build and shape the highly curved vesicular coat through the sequential
steps of initiating protein assembly, sensing membrane curvature, and driving membrane vesiculation.
Meanwhile hundreds of distinct transmembrane cargo proteins compete for space within the crowded
environment of the nascent vesicle. While it is clear that multiple protein components must work simultaneously
to execute each step, most of what we know about their molecular mechanisms is premised on studies of
individual proteins and domains in isolation from one another. How might individual mechanisms work together
in a heterogeneous environment? Can novel mechanisms emerge from the simultaneous action of multiple
individual remodeling proteins? Is the “whole” greater than “the sum of its parts”? Based on substantial published
and preliminary results from the first 3.5 years of this project, our central hypothesis is that assembly of multi-
component protein networks can synergistically amplify the contributions of individual proteins to key steps of
trafficking vesicle biogenesis. Aim 1 will quantify the role of protein networks in membrane curvature sensing
and vesiculation. Recently we have demonstrated that seemingly disparate physical mechanisms can work
together synergistically to sense membrane curvature and remodel membrane surfaces. These results support
our working hypothesis- assembly of protein networks can functionally and synergistically combine multiple
mechanisms of membrane remodeling. To test this hypothesis, we will investigate the collaboration between
membrane scaffolding, helix insertion, and protein crowding in membrane curvature sensing and vesiculation in
vitro and in live cells. Aim 2 will evaluate the ability of protein phase separation to catalyze coated vesicle
assembly. Recently we have made the exciting discovery that Eps15 and FCHo, key nucleators of endocytic
vesicles, can assemble into protein droplets at membrane surfaces. Based on these findings, we will use in vitro
and live cell experiments to test the working hypothesis that phase-separated protein droplets provide a dynamic
platform for catalyzing coated pits by controlling their spatial and temporal assembly. Aim 3 will measure the
impact of cargo-cargo interaction networks on endocytic uptake. It is increasingly appreciated that the endocytic
uptake of each cargo protein is dependent upon the diverse network of other cargo proteins present at the cell
surface. Therefore, we will use model cargo and disease-related receptors to evaluate the working hypothesis
that the molecular content of CCPs depends directly on competition and collaboration among cargo molecules.
Significantly, this work will explain how diverse molecular mechanisms work together synergistically in trafficking
vesicle biogenesis, suggesting the innovative premise that the functi...

## Key facts

- **NIH application ID:** 9960525
- **Project number:** 5R01GM112065-07
- **Recipient organization:** UNIVERSITY OF TEXAS AT AUSTIN
- **Principal Investigator:** Jeanne Casstevens Stachowiak
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $368,897
- **Award type:** 5
- **Project period:** 2014-08-01 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9960525

## Citation

> US National Institutes of Health, RePORTER application 9960525, Protein Networks as Synergistic Drivers of Membrane Traffic (5R01GM112065-07). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9960525. Licensed CC0.

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