RhoBTB protein is an atypical member of the Rho family of small GTPases
Members of the RhoBTB subfamily of Rho GTPases are present in vertebrates, Drosophila, and Dictyostelium. RhoBTB proteins are characterized by a modular organization, consisting of a GTPase domain, a proline rich region, a tandem of two BTB (Broad-Complex, Tramtrack, and Bric a brac) domains, and a C-terminal region of unknown function. RhoBTB proteins may act as docking points for multiple components participating in signal transduction cascades. RhoBTB genes appeared upregulated in some cancer cell lines, suggesting a participation of RhoBTB proteins in the pathogenesis of particular tumors. Note that the Dictyostelium RacA GTPase domain is more closely related to Rac proteins than to RhoBTB proteins, where RacA actually belongs. Thus, the Dictyostelium RacA is not included here. Most Rho proteins contain a lipid modification site at the C-terminus; however, RhoBTB is one of few Rho subfamilies that lack this feature.