Septyny

Septins are cytoskeletal proteins that form the fourth component of the cytoskeleton.

These proteins self-assemble to form hetero-oligomeric structures such as filaments for binding with the cell membrane and other cytoskeletal components. Additionally, they form rings or cage-like structures that act as scaffolds for cytoskeletal proteins required for cell division.

Septins’ structures contain a variable N-terminal head, a conserved central GTP binding domain, and a coiled-coil C-terminal tail region.

The N-terminal has a lipid-binding polybasic region or α0 helix region that interacts with phosphoinositides in the cell membrane. The interaction promotes polymerization of septin filaments for compartmentalization of the membrane.

The binding of GTP to the central GTP-binding domain and its rapid hydrolysis help form septin dimers. The GDP bound septin dimers polymerize into linear septin filaments.

The coiled-coil C-terminal tail allows filament assembly by forming inter-filament bridges between the different septin filaments.