Loss of the Dictyostelium RasC protein alters vegetative cell size, motility and endocytosis.

In addition to its previously established roles in cAMP relay and cAMP chemotaxis, loss of signal transduction through the RasC protein was found to impact a number of vegetative cell functions. Vegetative rasC- cells exhibited reduced random motility, were less polarized and had altered F-actin distribution. Cells lacking RasC also contained more protein and were larger in size than wild type cells. These increases were associated with increased liquid phase endocytosis. Despite the increase in cell size, cytokinesis was relatively normal and there was no change in the rate of cell division. rasC- cells also chemotaxed poorly to folate and exhibited reduced F-actin accumulation, reduced ERK2 phosphorylation and reduced Akt/PKB phosphorylation in response to folate, indicating that RasC was also involved in transducing chemotactic signals in vegetative cells.