module: dmel_bloc_borc_complexes
title: BLOC and BORC complexes in Drosophila melanogaster
label: BLOC and BORC complexes
module_type: PROTEIN_COMPLEX
description: >-
  The biogenesis of lysosome-related organelles complexes BLOC-1, BLOC-2 and
  BLOC-3 are needed to form lysosome-related organelles such as melanosomes in
  mammals and pigment granules in Drosophila eyes. BLOC-1 is an
  eight-subunit complex of small coiled-coil proteins (including dysbindin,
  pallidin, muted and snapin) that cooperates with endosomal sorting to deliver
  cargo to these organelles. BLOC-2 contains the HPS3, HPS5 and HPS6 subunits
  in mammals; the Drosophila HPS5 homolog is pink (p). BLOC-3, a heterodimer of
  HPS1 and HPS4, is a guanine nucleotide exchange factor for Rab32 and Rab38
  in mammals. BORC is a related complex that shares Blos1, Blos2 and Snapin
  with BLOC-1 and adds BORCS5, BORCS6, BORCS7, BORCS8 and KXD1 subunits; it
  recruits Arl8 to lysosomes and controls their positioning.
summary: >-
  BLOC-1, BLOC-2 and BLOC-3 for lysosome-related organelle biogenesis and the
  BLOC-1-related complex BORC for lysosome positioning.
concepts:
  - {id: GO:0031083, label: BLOC-1 complex}
  - {id: GO:0031084, label: BLOC-2 complex}
  - {id: GO:0031085, label: BLOC-3 complex}
  - {id: GO:0099078, label: BORC complex}
notes: >-
  Decomposition. Each complex is one part. Blos1, Blos2 and Snapin are shared
  by BLOC-1 and BORC and appear in both parts. FlyBase places CG14562 in
  BLOC-2 without a clear mammalian ortholog name; it is kept as listed. The
  Rab32/Rab38 exchange activity of BLOC-3 is established in mammals and is not
  asserted here for Drosophila.
parts:
  - id: bloc_1
    label: BLOC-1
    role: lysosome-related organelle cargo delivery
    group: BLOC1
    complex_term: {id: GO:0031083, label: BLOC-1 complex}
    processes:
      - {id: GO:0048753, label: pigment granule organization}
  - id: bloc_2
    label: BLOC-2
    role: lysosome-related organelle biogenesis
    group: BLOC2
    complex_term: {id: GO:0031084, label: BLOC-2 complex}
  - id: bloc_3
    label: BLOC-3
    role: Rab32/Rab38 exchange factor (in mammals)
    group: BLOC3
    complex_term: {id: GO:0031085, label: BLOC-3 complex}
  - id: borc
    label: BORC
    role: lysosome positioning
    group: BORC
    complex_term: {id: GO:0099078, label: BORC complex}
    processes:
      - {id: GO:0032418, label: lysosome localization}
function_note: >-
  No molecular function is assigned to any of the complexes: BLOC-1, BLOC-2
  and BORC are adaptor and scaffold complexes with no established catalytic
  activity, and the BLOC-3 exchange activity is not asserted (see above).