Molecular mechanism of 7TM receptor activation--a global toggle switch model
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Molecular mechanism of 7TM receptor activation--a global toggle switch model. / Schwartz, Thue W; Frimurer, Thomas M; Holst, Birgitte; Rosenkilde, Mette M; Elling, Christian E.
In: Annual Review of Pharmacology and Toxicology, Vol. 46, 2006, p. 481-519.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Molecular mechanism of 7TM receptor activation--a global toggle switch model
AU - Schwartz, Thue W
AU - Frimurer, Thomas M
AU - Holst, Birgitte
AU - Rosenkilde, Mette M
AU - Elling, Christian E
N1 - Keywords: Animals; Cytoplasm; Humans; Models, Molecular; Molecular Conformation; Receptor, Muscarinic M2; Receptors, G-Protein-Coupled
PY - 2006
Y1 - 2006
N2 - The multitude of chemically highly different agonists for 7TM receptors apparently do not share a common binding mode or active site but nevertheless act through induction of a common molecular activation mechanism. A global toggle switch model is proposed for this activation mechanism to reconcile the accumulated biophysical data supporting an outward rigid-body movement of the intracellular segments, as well as the recent data derived from activating metal ion sites and tethered ligands, which suggests an opposite, inward movement of the extracellular segments of the transmembrane helices. According to this model, a vertical see-saw movement of TM-VI-and to some degree TM-VII-around a pivot corresponding to the highly conserved prolines will occur during receptor activation, which may involve the outer segment of TM-V in an as yet unclear fashion. Small-molecule agonists can stabilize such a proposed active conformation, where the extracellular segments of TM-VI and -VII are bent inward toward TM-III, by acting as molecular glue deep in the main ligand-binding pocket between the helices, whereas larger agonists, peptides, and proteins can stabilize a similar active conformation by acting as Velcro at the extracellular ends of the helices and the connecting loops.
AB - The multitude of chemically highly different agonists for 7TM receptors apparently do not share a common binding mode or active site but nevertheless act through induction of a common molecular activation mechanism. A global toggle switch model is proposed for this activation mechanism to reconcile the accumulated biophysical data supporting an outward rigid-body movement of the intracellular segments, as well as the recent data derived from activating metal ion sites and tethered ligands, which suggests an opposite, inward movement of the extracellular segments of the transmembrane helices. According to this model, a vertical see-saw movement of TM-VI-and to some degree TM-VII-around a pivot corresponding to the highly conserved prolines will occur during receptor activation, which may involve the outer segment of TM-V in an as yet unclear fashion. Small-molecule agonists can stabilize such a proposed active conformation, where the extracellular segments of TM-VI and -VII are bent inward toward TM-III, by acting as molecular glue deep in the main ligand-binding pocket between the helices, whereas larger agonists, peptides, and proteins can stabilize a similar active conformation by acting as Velcro at the extracellular ends of the helices and the connecting loops.
U2 - 10.1146/annurev.pharmtox.46.120604.141218
DO - 10.1146/annurev.pharmtox.46.120604.141218
M3 - Journal article
C2 - 16402913
VL - 46
SP - 481
EP - 519
JO - Annual Review of Pharmacology and Toxicology
JF - Annual Review of Pharmacology and Toxicology
SN - 0362-1642
ER -
ID: 10536194