PT  - JOURNAL ARTICLE
AU  - Xi Wang
AU  - Xi Cheng
AU  - Lihua Zhao
AU  - Yuzhe Wang
AU  - Chenyu Ye
AU  - Xinyu Zou
AU  - Antao Dai
AU  - Zhaotong Cong
AU  - Jian Chen
AU  - Qingtong Zhou
AU  - Tian Xia
AU  - Hualiang Jiang
AU  - Eric H. Xu
AU  - Dehua Yang
AU  - Ming-Wei Wang
TI  - Molecular insights into differentiated ligand recognition of the human parathyroid hormone receptor 2
AID  - 10.1101/2021.06.09.447485
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.06.09.447485
4099  - http://biorxiv.org/content/early/2021/06/10/2021.06.09.447485.short
4100  - http://biorxiv.org/content/early/2021/06/10/2021.06.09.447485.full
AB  - The parathyroid hormone receptor 2 (PTH2R) is a class B1 G protein-coupled receptor (GPCR) involved in regulation of calcium transport, nociception mediation, and wound healing. Naturally occurring mutations in PTH2R were reported to cause hereditary diseases, including syndromic short stature. Here we report the cryo-electron microscopy structure of PTH2R bound to its endogenous ligand, tuberoinfundibular peptide (TIP39), and a heterotrimeric Gs protein at a global resolution of 2.8 Å. The structure reveals that TIP39 adopts a unique loop conformation at N terminus and deeply inserts into the orthosteric ligand-binding pocket in the transmembrane (TM) domain. Molecular dynamics (MD) simulation and site-directed mutagenesis studies uncover the basis of ligand specificity relative to three PTH2R agonists, TIP39, PTH, and PTH-related peptide (PTHrP). We also compare the action of TIP39 with an antagonist lacking six residues from the peptide N terminus, TIP(7–39), which underscores the indispensable role of the N terminus of TIP39 in PTH2R activation. Additionally, we unveil that a disease-associated mutation G258D significantly diminished cAMP accumulation induced by TIP39. Together, these results not only provide structural insights into ligand specificity and receptor activation of class B1 GPCRs, but also offer a foundation to systematically rationalize the available pharmacological data to develop novel therapies for various disorders associated with PTH2R.Competing Interest StatementThe authors have declared no competing interest.