# Functional Dynamics of P-glycoprotein

> **NIH NIH R01** · UNIVERSITY OF WASHINGTON · 2020 · $299,338

## Abstract

Project Summary
P-glycoprotein (P-gp) is an ATP-dependent efflux transporter that plays a critical role in drug
and xenobiotic distribution, drug-drug interactions, and drug-nutrient interactions. Efforts to
modulate P-gp activity to control cellular drug resistance or to modulate the action of existing
drugs have been only modestly successful. A barrier to progress in the design of P-gp inhibitors
has been the uncertainty about its catalytic mechanism. Different types of drugs or ligands elicit
different behaviors, wherein some stimulate ATP hydrolysis and are transported, while others
stimulate ATP hydrolysis but are not transported. Other drugs inhibit P-gp without stimulating
ATP hydrolysis. The mechanism by which different drugs elicit different behaviors is unclear.
Specifically, the conformational changes that mediate communication between the nucleotide
binding domains (NBDs) that hydrolyze ATP and the transmembrane helices (TMHs) that bind
and release xenobiotics remain unknown. One aim of this proposal is to map by H/D exchange
mass spectrometry the ligand-dependent conformational changes in the NBDs and the TMHs.
This will be performed with Pgp incorporated into lipid bilayer nanodiscs of defined lipid
composition. By monitoring the nucleotide-dependent and drug-dependent changes in solvent
exposure and dynamics of specific peptides in the sequence of each protein, with inhibitors,
substrates, uncouplers and allosteric modulators, the conformational changes that correlate with
each behavior will be identified. A second aim of these studies is to measure the on rates and
off rates of drug binding to and dissociating from P-gp in varying conformational states. There
are currently no data concerning these rates, which are likely to define ligand behavior, as a
substrate vs. inhibitor vs. uncoupler. These measurements will be made via surface plasmon
resonance and fluorescence correlation spectroscopy with P-gp nanodiscs. In order to correlate
the conformational mapping and off rate information with physiologic behavior, cell based
transport activity will be measured for representative drugs with different behaviors. Finally, this
proposal aims to explore the methodological advancements offered by nanodiscs with an
related drug transporter, BCRP. These studies will add methodological infrastructure to the
larger transporter field, increase our fundamental understanding of P-gp, further inform
pharmacokinetic models, and facilitate drug design aimed to modulate P-gp.

## Key facts

- **NIH application ID:** 9840486
- **Project number:** 5R01GM121603-04
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** WILLIAM M ATKINS
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $299,338
- **Award type:** 5
- **Project period:** 2017-01-01 → 2021-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9840486

## Citation

> US National Institutes of Health, RePORTER application 9840486, Functional Dynamics of P-glycoprotein (5R01GM121603-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9840486. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*