septinen

Septinen, known in English as septins, are a family of GTP-binding cytoskeletal proteins that form hetero-oligomeric complexes and higher-order filaments. They are conserved across fungi, animals, and many plants, and play core roles in cell division, polarity, and membrane remodeling.

Individual septin subunits contain a central GTPase domain and flanking coiled-coil regions. Members assemble into hexameric or octameric core complexes that polymerize into filaments. GTP binding and hydrolysis regulate assembly and disassembly, and interactions with phospholipids help target septins to membranes.

In cells, septin filaments often organize into ring-like structures at division sites, such as the mother–daughter neck in budding yeast and the cytokinetic apparatus in animal cells. These structures act as scaffolds for recruiting other proteins, as diffusion barriers to compartmentalize membranes, and as organizers for cytoskeletal elements involved in cytokinesis, vesicle trafficking, and cell polarity. In addition, septins participate in ciliogenesis and neuronal development, and influence exocytosis and membrane remodeling.

Different SEPT genes encode the subunits (for example SEPT2, SEPT6, SEPT7, SEPT9, and others). Aberrant septin expression or mutations have been linked to diseases including cancer, neurodevelopmental disorders, and hereditary neuropathies in some contexts. Research uses structural biology methods, fluorescence imaging, and genetic perturbation to elucidate septin assembly and function.