MAP KINASE FUNCTION IN AMEBOID CHEMOTAXIS

Mutants lacking the MAP kinase DdERK2 show reduced chemotactic respons es to folate and cAMP. Analysis of cAMP chemotaxis shows that Dderk2(- ) cells are defective in chemotaxis to high concentrations of cAMP. Th is defect is due to an inability to repolarize in the continued presen ce of high concentrations of cAMP. Under these conditions, the speed o f movement of mutant cells remains low Instead of generating a leading pseudopod, mutant cells generate transient crown-like structures over multiple regions of the cell surface. These structures differ from ps eudopods in that they contain myosin II as well as F actin and coronin . These studies identify a role for MAP kinases in coordinating the fo rmation of cell projections generated in response to chemoattractants.