G-protein gamma like domains (GGL) are found in the gamma subunit of the heterotrimeric G protein complex and in regulators of G protein signaling (RGS) proteins [1]. It is also found fused to an inactive Galpha in the Dictyostelium protein gbqA [2]. G-gamma likely shares a common origin with the helical N-terminal unit of G-beta [2]. All organisms that posses a G-beta possess a G-gamma [2].

1: A G protein gamma subunit-like domain shared between RGS11 and other RGS proteins specifies binding to Gbeta5 subunits. Snow BE, Krumins AM, Brothers GM, Lee SF, Wall MA, Chung S, Mangion J, Arya S, Gilman AG, Siderovski DP; Proc Natl Acad Sci U S A 1998;95:13307-13312. PMID:9789084

2: Comparative genomics uncovers novel structural and functional features of the heterotrimeric GTPase signaling system. Anantharaman V, Abhiman S, de Souza RF, Aravind L; Gene. 2011;475:63-78. PMID:21182906