# Structure, function, and inhibition of G protein-coupled receptor kinases

> **NIH NIH R01** · PURDUE UNIVERSITY · 2020 · $634,421

## Abstract

Project Summary
G protein-coupled receptor (GPCR) kinases (GRKs) phosphorylate activated GPCRs at multiple sites within
their cytoplasmic loops and C-terminal tails, leading to the recruitment of arrestins, uncoupling of the receptors
from heterotrimeric G proteins, and subsequently their internalization. Although GRK activity in healthy cells
allows them to adapt and avoid damage from sustained signaling, maladaptive overexpression of GRKs is
strongly associated with different pathologies including cardiovascular diseases such as heart failure and
maladaptive cardiac hypertrophy. A critical gap in our understanding of these processes is how GRKs
recognize activated GPCRs and how these GPCRs in turn activate the GRKs. Although we have been
successful at generating selective and potent inhibitors of GRK2, another critical gap is the lack of validated
chemical probes for GRK5, which plays a distinct role from GRK2 in cardiovascular disease although both
have been shown to be up-regulated in failing human myocardium. During the last funding cycle, our lab
developed derivatives of paroxetine, an FDA approved drug, that potently and selectively inhibit GRK2 activity
in vitro and in vivo, and that improve heart failure outcomes relative to paroxetine alone in myocardial infarcted
mice. We have now also identified a class of covalent inhibitors based on a different scaffold that are specific
for GRK5. Furthermore, we developed methodology to trap an agonist and GRK-ligand dependent GRK–
GPCR complex that is suitable for structural analysis by cryo electron microscopy (cryo-EM). In the first aim of
this competitive renewal, we will further develop and characterize analogs of the GRK2 and GRK5 subfamilies
based on the structure-activity relationships we have previously established. The best inhibitors will be
evaluated in cell-based and animal models relevant to human disease and will be used assess the relative
importance of GRK2 and GRK5 in cardiac physiology and disease. In the second aim, we will perform a cryo-
EM single particle reconstruction of the GRK1-rhodopsin complex, use this complex to select for nanobodies
that specifically recognize the complex, and extend our methodology to other GRK–receptor assemblies.
Collectively, our studies will contribute to a chemical “tool box” that can be used to help decipher the function of
specific GRKs in living cells and disease states, and that can be exploited to achieve a better understanding of
how GRKs interact with cellular targets using biophysical approaches.

## Key facts

- **NIH application ID:** 9998439
- **Project number:** 2R01HL071818-16
- **Recipient organization:** PURDUE UNIVERSITY
- **Principal Investigator:** John Tesmer
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $634,421
- **Award type:** 2
- **Project period:** 2004-01-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9998439

## Citation

> US National Institutes of Health, RePORTER application 9998439, Structure, function, and inhibition of G protein-coupled receptor kinases (2R01HL071818-16). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9998439. Licensed CC0.

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