| Type | subunit | Description | Septins polymerize into heterooligomeric protein complexes that form filaments, and associate with cellular membranes, actin filaments and microtubules. GTPase activity is required for filament formation. Filaments are assembled from asymmetrical heterotrimers, composed of SEPTIN2, SEPTIN6 and SEPTIN7 that associate head-to-head to form a hexameric unit. Within the trimer, directly interacts with SEPTIN6, while interaction with SEPTIN2 seems indirect. In the absence of SEPTIN6, forms homodimers. Interacts directly with CENPE and links CENPE to septin filaments composed of SEPTIN2, SEPTIN6 and SEPTIN7. Interacts with SEPTIN8, SEPTIN9 and SEPTIN11. Component of a septin core octomeric complex consisting of SEPTIN12, SEPTIN7, SEPTIN6 and SEPTIN2 or SEPTIN4 in the order 12-7-6-2-2-6-7-12 or 12-7-6-4-4-6-7-12 and located in the sperm annulus; the SEPTIN12:SEPTIN7 association is mediated by the respective GTP-binding domains (By similarity). Interacts with SEPTIN2 and SEPTIN5 (PubMed:11739749). |
