Chemotaxis: signalling modules join hands at front and tail

Chemotaxis is the result of a refined interplay among various intracellular molecules that process spatial and temporal information. Here we present a modular scheme of the complex interactions between the front and the back of cells that allows them to navigate. First, at the front of the cell, activated Rho‐type GTPases induce actin polymerization and pseudopod formation. Second, phosphatidylinositol‐3,4,5‐trisphosphate (PtdIns(3,4,5)P 3 ) is produced in a patch at the leading edge, where it binds pleckstrin‐homology‐domain‐containing proteins, which enhance actin polymerization and translocation of the pseudopod. Third, in Dictyostelium amoebae, a cyclic‐GMP‐signalling cascade has been identified that regulates myosin filament formation in the posterior of the cell, thereby inhibiting the formation of lateral pseudopodia that could misdirect the cell.