# Structural Basis of PTH Receptor Function

> **NIH NIH R01** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2020 · $429,297

## Abstract

Project Summary
The goal of this project is to determine structural mechanisms by which for the parathyroid hormone (PTH)
receptor (PTHR) signals in response to its functionally distinct ligands: PTH, PTH-related peptide (PTHrP) and
the long-acting PTH analog (LA-PTH). The PTHR is a major G protein-coupled receptor (GPCR) that regulates
Ca2+ homeostasis in blood and bone turnover, and is the most effective therapeutic target for osteoporosis. It
also is one of the first GPCR found to sustain cAMP production after internalization of the PTH–receptor
complex in endosomes. The recently recognized feature that the calcemic action of PTHR in mice and
primates is sustained by LA-PTH, which also prolongs endosomal cAMP production, is changing our thinking
about how PTHR mediates its physiological actions. Implicit in these findings is that efficient treatment of
hypocalcemia might be more approachable with selective targeting of PTHR-mediated endosomal cAMP
signaling. The mechanism that differentiating the signaling selectivity of PTH and its analogs are not known
and this is an obstacle to further move toward new directions to develop PTH-based therapies that have
improved efficacies for treating bone and mineral diseases. We therefore propose a research program to
overcome this obstacle. The goal of this project is thus to determine the structural basis by which PTHR
function and activate G proteins in response to PTH, PTHrP and LA-PTH.
 Two specific aims are proposed to discover structural basis of PTHR signaling. The first aim addresses
the hypothesis that PTH and LA-PTH promote long endosomal cAMP production by stabilizing unique
structural arrangements and phosphorylation pattern in the PTHR that are different from those stabilized by
PTHrP, which induces a short cAMP response from the plasma membrane. To this end, we will use
quantitative mass spectrometry (MS) based-proteomics technologies, such as Hydrogen-Deuterium exchange
coupled to MS (HDXMS) to determine structural changes and structural determinants for PTHR activation upon
binding to the distinct ligands, and identify the binding interface in PTHR–G protein complexes. The second
aim will complement our understanding of the functional selectivity of PTHR by X-ray crystallography of PTHR
and PTHR bound to PTH, PTHrP and LA-PTH. We have obtained X-ray diffractable crystals (4 Å) of the full
length PTHR bound to LA-PTH and in complex with the RNA polymerase II. Here we are using the cavity
formed in the RNA polymerase II crystal as a “crystal sponge” that creates a favorable crystallization
environment for PTHR. We will initially optimize the crystallization conditions to resolve crystal structure of the
PTHR bound to LA-PTH in complex with RNA polymerase II at higher resolution (2-3 Å). We will then focus of
resolving PTH and PTHrP-bound states of PTHR. These studies will provide new insights into how PTHR
activate G proteins and the structural mechanism differentiating the action of PTH, P...

## Key facts

- **NIH application ID:** 9895802
- **Project number:** 5R01DK116780-03
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** Jean-Pierre Vilardaga
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $429,297
- **Award type:** 5
- **Project period:** 2018-04-01 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9895802

## Citation

> US National Institutes of Health, RePORTER application 9895802, Structural Basis of PTH Receptor Function (5R01DK116780-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9895802. Licensed CC0.

---

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