module: dmel_septin_complexes
title: Septin complexes in Drosophila melanogaster
label: Septin complexes
module_type: PROTEIN_COMPLEX
description: >-
  Septins are GTP-binding proteins that assemble into hetero-oligomeric complexes,
  which polymerize into filaments and rings at the cell cortex. These structures act
  as scaffolds and diffusion barriers and are prominent at the cleavage furrow and
  the cellularization front. The best-characterized Drosophila septin complex
  contains Septin1, Septin2 and Peanut (Pnut), was purified from embryos and forms
  filaments in vitro; Pnut is needed for cytokinesis in proliferating tissues.
  Septin4 and Septin5, paralogs of Septin1 and Septin2, form a second complex with
  Pnut.
summary: >-
  Sep1-Sep2-Pnut and Sep4-Sep5-Pnut hetero-oligomeric septin complexes that form
  cortical filaments.
concepts:
  - {id: GO:0031105, label: septin complex}
variant_sets:
  - id: septin_complex_variants
    label: Septin complex paralog variants
    selection: ONE_OR_MORE
    variants:
      - id: sep1_sep2_pnut
        label: Septin1-Septin2-Pnut complex
        group: SEPT-C12P
        complex_term: {id: GO:0031105, label: septin complex}
        unit_functions:
          Septin1: {id: GO:0003924, label: GTPase activity}
          Septin2: {id: GO:0051015, label: actin filament binding}
          Septin4: {id: GO:0003924, label: GTPase activity}
          Septin5: {id: GO:0051015, label: actin filament binding}
          pnut: {id: GO:0003924, label: GTPase activity}
        processes:
          - {id: GO:0000910, label: cytokinesis}
      - id: sep4_sep5_pnut
        label: Septin4-Septin5-Pnut complex
        group: SEPT-C45P
        complex_term: {id: GO:0031105, label: septin complex}
        unit_functions:
          Septin1: {id: GO:0003924, label: GTPase activity}
          Septin2: {id: GO:0051015, label: actin filament binding}
          Septin4: {id: GO:0003924, label: GTPase activity}
          Septin5: {id: GO:0051015, label: actin filament binding}
          pnut: {id: GO:0003924, label: GTPase activity}
notes: >-
  Pnut is shared by both complexes and appears in each variant. The cytokinesis
  process is attached only to the Septin1-Septin2-Pnut complex, for which the
  genetic and biochemical evidence is strongest; the roles of the Septin4-Septin5
  complex are less well characterized. Septin-associated proteins such as anillin
  (scra) are context, not parts. GTPase activity (GO:0003924) is given only to
  Septin1, Septin4 (SEPT2 class) and Pnut (SEPT7 class). Septin2 and Septin5 are
  SEPT6-class septins: recombinant Sep2 shows no GTPase activity (NOT annotation,
  PMID:25355953), and the Septin2 and Septin5 gene reviews treat their GTPase
  annotations as removed or over-annotated, so these two subunits carry actin
  filament binding (GO:0051015) instead, the core activity in their reviews
  (PMID:38728140).
group: SEPT-C