Filament-forming cytoskeletal GTPase (By similarity). May play a role in cytokinesis (Potential). Septins polymerize into heterooligomeric protein complexes that form filaments, and can associate with cellular membranes, actin filaments and microtubules. GTPase activity is required for filament formation (By similarity). Expressed in the brain including the cerebrum, hippocampus and cerebellum (at protein level). Expressed in the cerebral cortex from 13.5 dpc to P30, expression peaks at P15. Phosphorylated by PKG on serine residues. Phosphorylated by PKG on Ser-91 (By similarity). Belongs to the TRAFAC class TrmE-Era-EngA-EngB-Septin-like GTPase superfamily. Septin GTPase family.