Septin (IPR016491)

Short name: Septin

Overlapping homologous superfamilies

Family relationships


This entry represents various septin proteins. These proteins were initially described in yeast, where a cross wall (septum) is produced during cytokinesis and then splits in certain organisms to allow the daughter cells to separate [PMID: 17596184]. However, the septin family is now recognised to extend to mammals and is associated with a variety of events. Septins are GTPases that form filaments used during cytokinesis in fungi and animals. Septins at the bud site serve as a structural scaffold that recruits different components involved in diverse processes at specific stages during the cell cycle. The septin assembly is regulated by protein kinases Gin4 and/or Cla4, and may act by recruiting Myo1 and Hof1 (involved in septation) to the site of cleavage. In addition to their original role in cell division, septins are also involved in cell morphogenesis, bud site selection, chitin deposition, cell cycle regulation, cell compartmentalisation, membrane trafficking, spore wall formation and organisation of the cytoskeleton. The localisation of a septin reflects its function [PMID: 17067846]:

  • Septins localising to projections help shape and compartmentalise emerging growth.
  • Septins localising to partitions help compartmentalise pre-existing cellular material.
  • Septins localising to the whole cell are involved in membrane trafficking and organising the cytoskeleton (usually in animals).

In yeast, septins encoded by Cdc3, Cdc10, Cdc11, Cdc12 and probably Shs1, form a septin complex localised at the cytoplasmic face of the plasma membrane in the mother-bud neck, where it rearranges to a cortical collar of highly ordered filaments [PMID: 16207085]. This complex can form long filaments through end-to-end polymerisation of Cdc3-Cdc12-Cdc11 complexes with Cdc10 serving as a bridge to bundle the polymers into paired filaments.

In humans, 12 septin genes generate dozens of polypeptides, many of which comprise heterooligomeric complexes. Since septin mutants are commonly defective in cytokinesis and formation of the neck filaments/septin rings, septins have been considered to be the primary constituents of the neck filaments [PMID: 12665577, PMID: 16207085, PMID: 12445407, PMID: 12888292, PMID: 12111093, PMID: 11916378].

In Drosophila, protein peanut is involved in cytokinesis, and is an enhancer of the sina gene, which has a role in photoreceptor development [PMID: 8181057].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005525 GTP binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.