Mutagenesis and modelling of the alpha(1b)-adrenergic receptor highlight the role of the helix 3/helix 6 interface in receptor activation.
Computer simulations on a new model of the alpha1b-adrenergic receptor based on the crystal structure of rhodopsin have been combined with experimental mutagenesis to investigate the role of residues in the cytosolic half of helix 6 in receptor activation. Our results support the hypothesis that a salt bridge between the highly conserved arginine (R143(3.50)) of the E/DRY motif of helix 3 and a conserved glutamate (E289(6.30)) on helix 6 constrains the alpha1b-AR in the inactive state. In fact, mutations of E289(6.30) that weakened the R143(3.50)-E289(6.30) interaction constitutively activated the receptor. The functional effect of mutating other amino acids on helix 6 (F286(6.27), A292(6.33), L296(6.37), V299(6.40,) V300(6.41), and F303(6.44)) correlates with the extent of their interaction with helix 3 and in particular with R143(3.50) of the E/DRY sequence.
Greasley
Peter J
PJ
Institut de Pharmacologie et Toxicologie, Université de Lausanne, Lausanne, Switzerland.
Fanelli
Francesca
F
Rossier
Olivier
O
Abuin
Liliane
L
Cotecchia
Susanna
S
D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D006224:Cricetinae; D008958:Models, Molecular; D016296:Mutagenesis; D017433:Protein Structure, Secondary; D018340:Receptors, Adrenergic, alpha-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D018340:Receptors, Adrenergic, alpha-1