A brain-specific G protein gamma subunit

Two different cDNAs for G protein γ subunits have been isolated from mouse brain. One encodes a novel γ subunit, γ4, the expression of which is detected only in brain. A fragment of this cDNA had been isolated previously. The other cDNA encodes γ3, a subunit type previously isolated from bovine brain. The primary structure of the γ3 subunit is conserved completely across species indicating that the diversity in the structure of the γ subunits is of functional consequence. Moreover, γ2, γ3 and γ4, which are predominantly expressed in brain, are more homologous to each other than other γ subunits, indicating that the G protein γ subunits belong to distinct subfamilies similar to the α subunits.