Neuromedin B receptor, expressed in Xenopus laevis oocytes, selectively couples to Gαq and not Gα11

G-proteins of the q family have been implicated as mediators of bombesin receptors action. We cloned Xenopus Gαq and Gα11 and specifically disrupted the synthesis of either protein with selective antisense oligonucleotides. Gαq antisense inhibited responses mediated by neuromedin B receptor (NMB-R) by 74%, though not by gastrin-releasing peptide receptor (GRP-R). Gα11 antisense had little effect on either GRP-R- or NMB-R-mediated responses. This suggests that NMB-R couples to Gαq, and that GRP-R and NMB-R show distinct G-protein coupling preferences in the Xenopus oocyte.