Summary.
Although it is known that GABAB receptors are negatively coupled to adenylyl cyclase, the detailed selectivity of functional interaction between GABAB receptors and Gi subfamily members is still ambiguous. (±)-Baclofen-stimulated high-affinity GTPase activity, which was competitively antagonized by 2-hydroxy-saclofen, was attenuated by pretreatment of the membranes with N-ethylmaleimide (NEM) in a concentration- and incubation period-dependent manner. The NEM-pretreated (50 μM, 15 min at 4°C) membranes restored the (±)-baclofen-sensitive high-affinity GTPase activity when reconstituted with pertussis toxin-sensitive bovine brain G proteins. Among recombinant rat Gα subunits, Giα−2 appeared most effective as compared with other subunits (Giα−2 > Giα−3 > Giα−1 = Goα). The GABAB receptor-mediated high-affinity GTPase activity was also completely eliminated by 100 μM suramin and by 100 μM benzalkonium chloride. These results indicate that GABAB receptors in rat cerebral cortex couple to NEM-sensitive G proteins, in particular Gi2, which are sensitive to suramin and benzalkonium chloride.
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Received September 6, 1999; accepted March 6, 2000
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Odagaki, Y., Nishi, N. & Koyama, T. Functional coupling of GABAB receptors with G proteins that are sensitive to N-ethylmaleimide treatment, suramin, and benzalkonium chloride in rat cerebral cortical membranes. J Neural Transm 107, 1101–1116 (2000). https://doi.org/10.1007/s007020070024
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DOI: https://doi.org/10.1007/s007020070024