module: dmel_cop9_signalosome
title: COP9 signalosome in Drosophila melanogaster
label: COP9 signalosome
module_type: PROTEIN_COMPLEX
description: >-
  The COP9 signalosome (CSN) is an eight-subunit complex that removes the
  ubiquitin-like protein Nedd8 from cullins, thereby controlling the activity
  and assembly of cullin-RING ubiquitin ligases. Six subunits (CSN1, CSN2, CSN3,
  CSN4, CSN7 and CSN8) contain PCI domains and form a horseshoe-shaped
  scaffold, and two subunits (CSN5 and CSN6) contain MPN domains; CSN5 is the
  JAMM metalloprotease that carries the deneddylase activity. Drosophila has
  two CSN1 paralogs: CSN1b in the ubiquitous complex and CSN1a in a
  testis-specific variant. The Drosophila CSN2 subunit is encoded by alien.
summary: >-
  Eight-subunit cullin deneddylase complex with a CSN5 JAMM catalytic subunit
  and ubiquitous (CSN1b) or testis-specific (CSN1a) variants.
concepts:
  - {id: GO:0008180, label: COP9 signalosome}
parts:
  - id: pci_scaffold
    label: PCI-domain scaffold subunits
    role: PCI scaffold
    genes: [alien, CSN3, CSN4, CSN7, CSN8]
  - id: csn1
    label: CSN1 subunit
    role: PCI subunit, variant-specific
    variant_sets:
      - id: csn1_paralogs
        label: CSN1b (ubiquitous) or CSN1a (testis-specific)
        selection: EXACTLY_ONE
        variants:
          - {id: csn1b_variant, label: CSN1b ubiquitous complex, genes: [CSN1b]}
          - {id: csn1a_testis_variant, label: CSN1a testis-specific complex, genes: [CSN1a]}
  - id: mpn_catalytic
    label: CSN5-CSN6 MPN dimer
    role: catalytic deneddylase module
    genes: [CSN5, CSN6]
    unit_functions:
      CSN5: {id: GO:0019784, label: deNEDDylase activity}
    processes:
      - {id: GO:0000338, label: protein deneddylation}
notes: >-
  FlyBase subgroups COP9 and COP9-T share seven subunits and differ only in
  CSN1b versus CSN1a; the shared subunits are modelled once. CSN1 is a PCI
  subunit but is modelled as its own part to hold the paralog variants.