A docking site for G protein βγ subunits on the parathyroid hormone 1 receptor supports signaling through multiple pathways.
The G protein-coupled receptor for PTH and PTH-related protein (PTH1R) signals via many intracellular pathways. The purpose of this work is to investigate a G protein binding site on an intracellular domain of the PTH1R. The carboxy-terminal, cytoplasmic tail of the PTH1R fused to glutathione-S-transferase interacts with Gi/o proteins in vitro. All three subunits of the heterotrimer interact with the receptor C-tail. Activation of the heterotrimeric complex with GTPgammaS has no effect on Gbetagamma interactions, but markedly disrupts binding of the Galphai/o subunits to the receptor tail, suggesting that direct Gbetagamma binding indirectly links Galpha subunits to this region of the receptor. Gbetagamma subunits alone bind the C-tail with an affinity that is comparable to the heterotrimeric G protein complex. G protein complexes consisting of Galphashis6-beta1gamma2 and Galphaqhis6-beta1gamma2 also interact with the PTH1R tail in vitro. The Gbetagamma interaction domain is located on the juxta-membrane region of the tail between amino acids 468 and 491. Mutations that disrupt Gbetagamma interactions block PTH signaling via phospholipase Cbeta/[Ca2+]i and MAPK and markedly reduce signaling via adenylyl cyclase/cAMP. Herein, we define a domain on the PTH1R that is capable of binding G protein heterotrimeric complexes via direct Gbetagamma interactions.
Mahon
Matthew J
MJ
Endocrine Unit, Massachusetts General Hospital, Boston, Massachuesetts 02114, USA. mahon@helix.mgh.harvard.edu
Bonacci
Tabetha M
TM
Divieti
Paola
P
Smrcka
Alan V
AV
D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D019281:Dimerization; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000235:genetics / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D054799:Phospholipase C beta; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism
D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D007527:Isoenzymes; D021122:Protein Subunits; D044168:Receptor, Parathyroid Hormone, Type 1; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000242:Cyclic AMP; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D000262:Adenylyl Cyclases; D002118:Calcium