NEUROMEDIN-B RECEPTOR, EXPRESSED IN XENOPUS-LAEVIS OOCYTES, SELECTIVELY COUPLES TO G(ALPHA-Q) AND NOT G(ALPHA-11)

G-proteins of the q family have been implicated as mediators of bombesin receptors action. We cloned Xenopus G(alpha q) and G(alpha 11) and specifically disrupted the synthesis of either protein with selective antisense oligonucleotides. G(alpha q) antisense inhibited responses mediated by neuromedin B receptor (NMB-R) by 74%, though not by gastrin-releasing peptide receptor (GRP-R). G(alpha 11) antisense had little effect on either GRP-R- or NMB-R-mediated responses. This suggests that NMB-R couples to G(alpha q) and that GRP-R and NMB-R show distinct G-protein coupling preferences in the Xenopus oocyte.