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Preassociation between the 5‐HT 7 serotonin receptor and G protein G s : molecular determinants and association with low potency activation of adenylyl cyclase
Author(s) -
Ulsund Andrea Hembre,
Dahl Marie,
Frimurer Thomas M.,
Manfra Ornella,
Schwartz Thue W.,
Levy Finn Olav,
Andressen Kjetil Wessel
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.201800805rr
Subject(s) - g protein coupled receptor , agonist , receptor , 5 ht7 receptor , adenylyl cyclase , 5 ht5a receptor , 5 ht1 receptor , endogenous agonist , g protein , gs alpha subunit , 5 ht receptor , functional selectivity , g protein coupled receptor kinase , signal transduction , chemistry , biology , microbiology and biotechnology , serotonin , biochemistry , dopamine receptor d1
According to early models of GPCR signaling, G proteins only interact with activated receptors. However, some GPCRs were shown to assemble with G proteins before receptor activation, in accordance with more recent models. Previously, we found that the 5‐HT 7 receptor, as opposed to the 5‐HT 4 receptor, was preassociated with G s , but the molecular determinants for this interaction are still elusive. In a series of chimeric 5‐HT 7 receptors with intracellular segments from 5‐HT 4 , we determined the receptor–G protein interaction by performing antibody‐immobilized fluorescence recovery after photobleaching and fluorescence resonance energy transfer. We identified the intracellular loop 3 and C‐tail of the 5‐HT 7 receptor to be responsible for the preassociation with G s , and we further delineated the TM5 extension in the intracellular loop 3 and helix 8 in the C‐tail as the molecular determinants. These chimeric exchanges converted the 5‐HT 7 receptor into a collision‐coupled receptor that recruited G proteins only upon agonist activation, whereas reciprocal exchanges converted 5‐HT 4 to a preassociated receptor. The 5‐HT 7 receptor displayed 2‐component agonist‐induced G s signaling with high and low potency. In addition, the same segments were involved in low‐potency signaling and preassociation. The correspondence between G s preassociation and low‐potency G s signaling is a novel aspect of GPCR pharmacology.—Ulsund, A. H., Dahl, M., Frimurer, T. M., Manfra, O., Schwartz, T. W., Levy, F. O., Andressen, K. W. Preassociation between the 5‐HT 7 serotonin receptor and G protein G s : molecular determinants and association with low potency activation of adenylyl cyclase. FASEB J. 33, 3870–3886 (2019). www.fasebj.org