module: dmel_mrna_nuclear_export
title: mRNA nuclear export machinery in Drosophila melanogaster
label: mRNA nuclear export
module_type: BIOLOGICAL_PROCESS
description: >-
  Bulk export of mRNA from the nucleus is coupled to transcription and
  processing. The TREX complex, consisting of the THO subcomplex with the
  DEAD-box helicase Hel25E (UAP56) and the adaptor Ref1 (ALY), is loaded
  onto nascent mRNA and hands it to the export receptor heterodimer formed by
  sbr (NXF1) and Nxt1, which carries the mRNP through the nuclear pore complex
  by interacting with FG-repeat nucleoporins. TREX-2 (xmas, PCID2 and e(y)2)
  associates with the nuclear pore and couples transcription with export; in
  Drosophila it links actively transcribed genes to the nuclear periphery and
  shares e(y)2 with the SAGA deubiquitinase module.
summary: >-
  TREX, TREX-2 and the Nxf1-Nxt1 receptor, which package and move mRNA out of
  the nucleus.
concepts:
  - {id: GO:0006406, label: mRNA export from nucleus}
cellular_components:
  - {id: GO:0005634, label: nucleus}
parts:
  - id: trex
    label: Transcription export complex
    role: mRNP packaging for export
    description: >-
      THO (Hpr1, tho2, thoc5, thoc6, thoc7) with Hel25E, Ref1 and tex (the
      Tex1 homolog).
    group: TREX
    complex: true
    complex_term: {id: GO:0000346, label: transcription export complex}
    unit_functions:
      Hel25E: {id: GO:0003724, label: RNA helicase activity}
  - id: nxf1_nxt1
    label: Nxf1-Nxt1 export receptor
    role: mRNP translocation through the nuclear pore
    group: NXF
    complex: true
  - id: trex2
    label: Transcription export complex 2
    role: nuclear pore-associated export and gene gating
    group: TREX-2
    complex: true
    complex_term: {id: GO:0070390, label: transcription export complex 2}
connections:
  - {source: trex, target: nxf1_nxt1, connection_type: PRECEDES, description: TREX loads the Nxf1-Nxt1 receptor onto the processed mRNP.}
notes: >-
  Boundary. FlyBase's THO-C group is entirely contained in TREX and is
  represented through the TREX part. Nuclear pore complex proteins, the exon
  junction complex and SAGA are outside the module. GO has no cellular-component
  term for the Nxf1-Nxt1 heterodimer, so that part has no complex term.