A brain-specific G protein gamma subunit.

Two different cDNAs for G protein gamma subunits have been isolated from mouse brain. One encodes a novel gamma subunit, gamma 4, the expression of which is detected only in brain. A fragment of this cDNA had been isolated previously. The other cDNA encodes gamma 3, a subunit type previously isolated from bovine brain. The primary structure of the gamma 3 subunit is conserved completely across species indicating that the diversity in the structure of the gamma subunits is of functional consequence. Moreover, gamma 2, gamma 3 and gamma 4, which are predominantly expressed in brain, are more homologous to each other than other gamma subunits, indicating that the G protein gamma subunits belong to distinct subfamilies similar to the alpha subunits.