Small GTPases in Dictyostelium: lessons from a social amoeba

Although the process of sequencing the Dictyostelium genome is not complete , it is already producing surprises, including an unexpectedly large number of Ras- and Rho-subfamily GTPases. Members of these families control a wid e variety of cellular processes in eukaryotes, including proliferation, dif ferentiation, cell motility and cell polarity. Comparison of small GTPases from Dictyostelium with those from higher eukaryotes provides an intriguing view of their cellular and evolutionary roles. In particular, although mam malian pas proteins interact with several signalling pathways, the Dictyost elium pathways appear more linear, with each pas apparently performing a sp ecific cellular function.