module: dmel_compass_family_complexes
title: COMPASS-family histone H3K4 methyltransferase complexes in Drosophila melanogaster
label: COMPASS-family complexes
module_type: PROTEIN_COMPLEX
description: >-
  Drosophila has three COMPASS-family complexes, each built around a different
  SET-domain histone H3 lysine 4 methyltransferase. Set1/COMPASS performs most
  bulk H3K4 di- and trimethylation, the Trithorax (Trx) complex maintains
  expression of Hox and other developmental genes against Polycomb silencing,
  and the Trithorax-related (Trr) complex monomethylates H3K4 at enhancers and
  carries the H3K27 demethylase Utx. All three share the WRAD core (Wds, Rbbp5,
  Ash2 and Dpy-30L1) that stimulates the methyltransferase. Trx is also found
  in TAC1, a complex with the CBP acetyltransferase Nejire and Sbf.
summary: >-
  Set1/COMPASS, Trx and Trr histone H3K4 methyltransferase complexes sharing
  the WRAD core, plus the Trx-CBP TAC1 complex.
concepts:
  - {id: GO:0035097, label: histone methyltransferase complex}
cellular_components:
  - {id: GO:0000785, label: chromatin}
parts:
  - id: compass_h3k4_methyltransferase_complexes
    label: COMPASS-type H3K4 methyltransferase complexes
    role: H3K4 methyltransferase complexes
    description: >-
      Three alternative complexes, each with one SET-domain methyltransferase
      and the shared WRAD core.
    variant_sets:
      - id: compass_variants
        label: Set1, Trx or Trr complexes
        selection: ONE_OR_MORE
        variants:
          - id: set1_compass
            label: Set1/COMPASS complex
            group: COMP
            complex_term: {id: GO:0048188, label: Set1C/COMPASS complex}
            unit_functions:
              Set1: {id: GO:0042800, label: histone H3K4 methyltransferase activity}
          - id: trx_complex
            label: Trx complex
            group: TRX-C
            complex_term: {id: GO:0044665, label: MLL1/2 complex}
            unit_functions:
              trx: {id: GO:0042800, label: histone H3K4 methyltransferase activity}
          - id: trr_complex
            label: Trr complex
            group: TRR
            complex_term: {id: GO:0044666, label: MLL3/4 complex}
            unit_functions:
              trr: {id: GO:0042800, label: histone H3K4 methyltransferase activity}
              Utx: {id: GO:0071558, label: histone H3K27me2/H3K27me3 demethylase activity}
  - id: tac1
    label: Trithorax acetylation complex 1
    role: Trx-CBP complex
    description: >-
      Complex of Trithorax with the CBP histone acetyltransferase Nejire and
      the SET domain binding factor Sbf.
    group: TAC1
    unit_functions:
      nej: {id: GO:0004402, label: histone acetyltransferase activity}
notes: >-
  The FlyBase COMPASS-type subgroups are modelled as alternative complexes,
  so the shared WRAD subunits (wds, Rbbp5, ash2, Dpy-30L1) and Hcf appear in
  more than one. The Trx and Trr complexes are grounded to the GO terms for
  their mammalian counterparts (MLL1/2 and MLL3/4). TAC1 (a separate FlyBase
  group) is a distinct part because it shares Trx but not the WRAD core.