"The gene GTP-binding-protein .... Its molecular function is described as: GTP binding; ubiquitin-protein ligase activity. It is involved in the biological process protein ubiquitination."
In looking at this, the 1995 reference that named it seems to have mis-identified this as a G-protein, based only on the fact that it has WD40 repeats.  This is now very outdated and simply wrong.  
There is no evidence that its a GTP binding protein (Even the beta subunit of the heterotrimeric G protein it weakly resembles is not--its the alpha subunit that binds GTP!!)!
realname: Mark Peifer