A conserved Asn in TM7 of the thyrotropin receptor is a common requirement for activation by both mutations and its natural agonist.
The wide spectrum of naturally occurring mutations able to activate the thyrotropin (TSH) receptor provides a useful tool to approach the structure of the active state(s) of the glycoprotein hormone receptors. Here we show that the side-chain of the highly conserved N7.49 (Asn 674) in TM7 is mandatory for activation of the TSH receptor, not only by TSH, but also by a panel of eight natural and two artificial activating mutations. Basal activity levels of the mutants were significantly decreased by suppression of the side-chain of N7.49 (N7.49A double mutants). In addition, comparative effects of the N7.49A substitution on the ten mutants demonstrate that basal activity and agonist- or mutation-stimulated activity might involve different structural changes.
Claeysen
Sylvie
S
IRIBHN, Université Libre de Bruxelles, Campus Erasme, 808 route de Lennik, B-1070, Brussels, Belgium
Govaerts
Cédric
C
Lefort
Anne
A
Van Sande
Jacqueline
J
Costagliola
Sabine
S
Pardo
Leonardo
L
Vassart
Gilbert
G
D000818:Animals; D001216:Asparagine / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011989:Receptors, Thyrotropin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013972:Thyrotropin / Q000378:metabolism*
D008562:Membrane Glycoproteins; D011989:Receptors, Thyrotropin; D001216:Asparagine; D013972:Thyrotropin; D000242:Cyclic AMP