Actin reorganization is important for the regulation of neuronal morphology. A protein involved in this process, the transducer of cdc42-dependent actin assembly 1 (TOCA-1) protein, a member of the evolutionarily conserved pombe CDC15 homology (PCH) protein family, is an essential component of the Cdc42 pathway. TOCA-1 binds both N-WASP and Cdc42 and is essential for Cdc42- and PIP2-induced actin polymerization, suggesting that TOCA-1 mediates Cdc42-dependent actin nucleation by activating the N-WASP-WIP complex. Decreased expression of TOCA-1 significantly enhances neurite elongation in PC-12 cells; its overexpression in the same cells suppresses neurite elongation. It has been suggested that TOCA-1 negatively regulates axon branching by regulating membrane trafficking by regulating membrane trafficking through the F-BAR/EFC domain. Multiple isoforms of TOCA-1 are known to exist.
