Localization of mRNAs encoding the α-subunits of signal-transducing G-proteins within rat brain and among peripheral tissues

The sequence of the mRNAs which encode the α-subunits of the signal-transducing G-proteins G_s, G_o and two forms of G_i (termed G_i1 and G_i2) have recently been reported. Based on rat sequences we prepared oligodeoxynucleotide probes for measurement of these mRNAs in rat brain and peripheral tissues. The relative abundance of these mRNA species in brain was G_s > G_o ∼ G_i2 > G_i1. The G_s and G_i2 mRNAs had somewhat lower levels in heart, kidney and liver than in brain, and G_o and G_i1 mRNAs were not detected in the peripheral tissues. Using in situ hybridization we localized each of these mRNAs within slices of the rat brain. The patterns of distribution of G_s and G_i2 mRNA were very similar, but very different from that of G_o and G_i1 mRNA. These data illustrate that receptor-effector coupling G-proteins are regionally specialized in their expression. This regional specialization may reflect a selective coupling of individual G-proteins with the various neurotransmitter receptors and effector pathways.