Allosteric interactions in the parathyroid hormone class B GPCR arrestin complex formation

ABSTRACT: Peptide ligands of class B GPCRs act via a two step binding process, but many gaps remain in our understanding of the essential mechanisms that link the extracellular binding of peptide ligands to intracellular receptor arrestin interaction. Using NMR, crosslinking coupled to mass spectrometry, signaling experiments, and computational approaches on the parathyroid hormone (PTH) type 1 receptor (PTHR), we show that the initial binding of the PTH C terminal part to the receptor constrains the conformation of the flexible N terminal signaling epitope of the PTH before a second binding event takes place. A hot spot PTH residue, His9, that inserts into the transmembrane domain of the PTHR at this second step allosterically engages receptor and arrestin coupling. The mechanism appears to elicit a conformational change in the receptor intracellular loop 3 (ICL3) that permits favorable interactions with the b arrestin finger loop. These results unveil structural determinants for PTHR arrestin complex formation and reveal that the two step binding mechanism proceeds via cooperative fluctuations between the peptide ligand and the receptor, which may be extended to other class B GPCRs.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Kunhong Xiao  

PROVIDER: MSV000084971 | MassIVE | Tue Feb 18 09:07:00 GMT 2020

REPOSITORIES: MassIVE