module: dmel_mon1_ccz1_complex
title: Mon1-Ccz1 Rab7 exchange factor complex in Drosophila melanogaster
label: Mon1-Ccz1 complex
module_type: PROTEIN_COMPLEX
description: >-
  The Mon1-Ccz1 complex is the guanine nucleotide exchange factor for Rab7.
  Recruited to endosomes by Rab5 and phosphoinositides, it activates Rab7 and
  thereby drives Rab5-to-Rab7 conversion during endosome maturation, and it
  also acts on autophagosomes. Active Rab7 recruits the HOPS tethering complex
  for fusion with lysosomes. In metazoans the complex contains a third
  subunit, RMC1, whose Drosophila ortholog is Bulli; it is needed for full
  activity of the complex in vivo.
summary: >-
  Rab7 guanine nucleotide exchange factor complex of Mon1, Ccz1 and Bulli that
  drives endosome and autophagosome maturation.
concepts:
  - {id: GO:0035658, label: Mon1-Ccz1 complex}
notes: >-
  Decomposition. Mon1 and Ccz1 form the catalytic heterodimer; Bulli (RMC1)
  is modelled as a separate accessory part because its precise contribution to
  activity and membrane targeting in vivo is less defined.
parts:
  - id: mon1_ccz1_heterodimer
    label: Mon1-Ccz1 heterodimer
    role: Rab7 GEF catalytic heterodimer
    genes: [Mon1, Ccz1]
    function: {id: GO:0005085, label: guanyl-nucleotide exchange factor activity}
  - id: bulli
    label: Bulli (RMC1)
    role: accessory subunit
    genes: [Bulli]
knowledge_gaps:
  - gap_statement: >-
      How Bulli contributes to the Mon1-Ccz1 complex, whether by stabilizing
      it, targeting it to membranes or modulating Rab7 exchange activity, is
      not established in Drosophila.
    boundary: Mechanistic role of the RMC1/Bulli subunit.
    gap_kind: [BIOLOGY]