module: dmel_smc5_6_complex
title: SMC5/6 complex in Drosophila melanogaster
label: SMC5/6 complex
module_type: PROTEIN_COMPLEX
description: >-
  The SMC5/6 complex is the third eukaryotic SMC complex, acting in DNA repair
  by homologous recombination, in the resolution of recombination and
  replication intermediates, and in the maintenance of repetitive DNA such as
  the rDNA and heterochromatin. It is built on an SMC5-SMC6 heterodimer
  bridged by the kleisin Nse4, which binds the Nse1-Nse3 pair (Nse3 is a
  MAGE-family protein, encoded in Drosophila by MAGE). The SUMO ligase subunit
  Nse2 binds the SMC arms. Drosophila has two Nse2 paralogs, Quijote (qjt) and
  Cervantes (cerv), which define two variants of the complex.
summary: >-
  SMC5-SMC6 heterodimer with Nse1-MAGE-Nse4 and one of two Nse2 SUMO ligase
  paralogs (Qjt or Cerv).
concepts:
  - {id: GO:0030915, label: Smc5-Smc6 complex}
cellular_components:
  - {id: GO:0005634, label: nucleus}
parts:
  - id: smc5_smc6
    label: SMC5-SMC6 heterodimer
    role: SMC ATPase core
    genes: [SMC5, SMC6]
    unit_functions:
      SMC5: {id: GO:0016887, label: ATP hydrolysis activity}
      SMC6: {id: GO:0016887, label: ATP hydrolysis activity}
  - id: nse1_nse3_nse4
    label: Nse1-MAGE-Nse4 subcomplex
    role: kleisin and kleisin-associated subunits
    genes: [Nse4, Nse1, MAGE]
  - id: nse2_sumo_ligase
    label: Nse2 SUMO ligase subunit
    role: SUMO ligase subunit
    variant_sets:
      - id: nse2_paralogs
        label: Nse2 paralogs
        selection: ONE_OR_MORE
        variants:
          - {id: nse2_qjt, label: Quijote (Nse2 paralog), genes: [qjt]}
          - {id: nse2_cerv, label: Cervantes (Nse2 paralog), genes: [cerv]}
notes: >-
  FlyBase defines the QJT and CERV variants (SMC5-6-T, SMC5-6-V) that differ
  only in the Nse2 paralog; the shared subunits are modelled once. SUMO ligase
  activity is not assigned to Qjt or Cerv because it is inferred from yeast
  and human Nse2 rather than shown for the fly proteins; for the same reason
  the ubiquitin ligase activity inferred for Nse1 (ISS) is not assigned. The SMC subunits are given ATP hydrolysis activity (GO:0016887), which
  they carry in GOA (ISS, NAS, IEA); their ATPase heads, engaged across the
  heterodimer, drive the complex. GO has a complex-level term for SMC-complex
  DNA entrapment (GO:0061776 ATP-dependent topological DNA co-entrapment
  activity, used by PomBase for the fission yeast complexes), but it is not
  annotated to the Drosophila proteins and is not asserted here.