Delineation of a region in the B2 bradykinin receptor that is essential for high-affinity agonist binding.

AUTOR(ES)

Nardone, J

RESUMO

We have made mutations in the predicted sixth transmembrane segment of a rat B2 bradykinin receptor and analyzed the variant proteins by expressing them in COS-1 cells. Two amino acid substitutions reduced the affinity of the receptor for bradykinin (Phe261-->Val by 1600-fold; Thr265-->Ala by 700-fold) with comparatively little effect on the affinity for the bradykinin antagonists NPC17731 and D-Arg-[Hyp3,D-Phe7]bradykinin (where Hyp is hydroxyproline). Three other substitutions (Gln262-->Ala, Asp268-->Ala, and Thr269-->Ala) modestly reduced the affinity for bradykinin and for the antagonist D-Arg-[Hyp3,D-Phe7]bradykinin. Even the most dramatically affected mutated receptors were still able to couple, after bradykinin binding, to phosphatidylinositol turnover. The data suggest that bradykinin directly contacts the face of the sixth transmembrane helix formed by the residues Phe261, Gln262, Thr265, Asp268, and Thr269 or that this face of the helix is the site of intraprotein contacts that serve to stabilize the agonist-binding conformation of the receptor.

Documentos Relacionados

• Mechanism of epidermal growth factor receptor autophosphorylation and high-affinity binding.
• High-affinity RNA ligands to basic fibroblast growth factor inhibit receptor binding.
• Reconstitution of high-affinity opioid agonist binding in brain membranes.
• Properties of a high-affinity DNA binding site for estrogen receptor.
• High-affinity laminin receptor is a receptor for Sindbis virus in mammalian cells.