module: dmel_copi_coat
title: COPI coatomer in Drosophila melanogaster
label: COPI coat
module_type: PROTEIN_COMPLEX
description: >-
  Coatomer is the heptameric coat of COPI vesicles, which mediate retrograde
  transport from the Golgi apparatus to the endoplasmic reticulum and
  transport between Golgi cisternae. Coatomer is recruited en bloc to
  membranes by the small GTPase Arf1 in its GTP-bound form and binds cargo
  with dilysine and related sorting signals. Structurally it consists of a
  B-subcomplex (alpha, beta' and epsilon subunits) that forms the outer
  cage-like layer and an F-subcomplex (beta, gamma, delta and zeta subunits)
  that resembles the clathrin adaptor complexes and contacts the membrane.
summary: >-
  Heptameric coatomer that coats COPI vesicles for Golgi-to-ER retrograde and
  intra-Golgi transport.
concepts:
  - {id: GO:0030126, label: COPI vesicle coat}
cellular_components:
  - {id: GO:0000139, label: Golgi membrane}
notes: >-
  Boundary. The module contains the seven coatomer subunits. The Arf1 GTPase
  (Arf79F in Drosophila), its GEFs and GAPs regulate coat recruitment and are
  context, not parts.
parts:
  - id: copi_b_subcomplex
    label: COPI B-subcomplex
    role: outer coat layer
    description: Alpha, beta' and epsilon coatomer subunits, which form the outer, cage-like layer of the coat.
    genes: [alphaCOP, beta'COP, epsilonCOP]
    processes:
      - {id: GO:0006890, label: "retrograde vesicle-mediated transport, Golgi to endoplasmic reticulum"}
  - id: copi_f_subcomplex
    label: COPI F-subcomplex
    role: adaptor-like inner coat layer
    description: Beta, gamma, delta and zeta coatomer subunits, the adaptor-like layer that contacts the membrane and cargo.
    genes: [betaCOP, gammaCOP, deltaCOP, zetaCOP]
    processes:
      - {id: GO:0006890, label: "retrograde vesicle-mediated transport, Golgi to endoplasmic reticulum"}
function_note: >-
  No molecular function is assigned: coatomer is treated as a structural
  vesicle coat, and its subunits carry only structural molecule activity (IEA)
  in GOA.