# Actin assembly and clathrin-mediated endocytosis in yeast and mammals

> **NIH NIH R35** · UNIVERSITY OF CALIFORNIA BERKELEY · 2022 · $1,028,284

## Abstract

PROJECT SUMMARY
Proposed are complementary studies on the mechanisms and regulation of clathrin-mediated endocytosis
(CME) and actin force generation during CME in budding yeast and human stem cells. CME is responsible for
uptake of molecules from a cell's environment through the permeability barrier of the plasma membrane and
for selective removal of plasma membrane proteins. It is also one of the main routes for COVID-19 to enter
cells. Therefore, this process is crucial for determining how cells respond to their surroundings and has
heightened translational significance. Many proteins and lipids that mediate CME have been identified and
their functions determined biochemically and in living cells. Imaging of fluorescently labeled CME proteins in
live cells has revealed the intricate recruitment timing and order for some 60 CME proteins. However, how
cargo capture is coordinated with vesicle formation, how correct protein recruitment order and timing are
achieved, which events and molecules play critical roles in the pathway, and how forces curve the membrane
and drive vesicle scission, are not fully understood. The following key questions will be addressed in budding
yeast and human stem cells: 1) How does membrane curvature affect biochemical reaction rates? 2) How
does CME become specialized for different cell types during differentiation? 3) How does a checkpoint sense
cargo and regulate CME progress? and, 4) How does actin assemble at CME sites and how does its
ultrastructure contribute to CME force production and adapt to increased membrane tension? Yeast studies will
be empowered by a rich legacy in the lab of elucidating actin assembly and force production mechanisms.
Human cell studies will be empowered by over 120 stable human tissue culture and stem cell lines generated
using genome editing to express CME and actin cytoskeleton proteins as fluorescent protein fusions at native,
endogenous levels. Because CME proteins are highly conserved in structure and function, principles learned
from studies of yeast and humans will complement and inform each other. Together, these studies will provide
a comprehensive mechanistic understanding that could not be achieved by studies in only one cell type.
Because the actin cytoskeleton has been adapted by evolution for diverse, essential activities including cell
motility, organelle transport, adhesion, and cell polarity development, what is learned will apply broadly for
many cellular processes and will join the growing armamentarium of possible defensive measures against the
pandemic.

## Key facts

- **NIH application ID:** 10434883
- **Project number:** 5R35GM118149-07
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** DAVID G DRUBIN
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $1,028,284
- **Award type:** 5
- **Project period:** 2016-07-01 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10434883

## Citation

> US National Institutes of Health, RePORTER application 10434883, Actin assembly and clathrin-mediated endocytosis in yeast and mammals (5R35GM118149-07). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10434883. Licensed CC0.

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