module: dmel_mrn_complex
title: Mre11-Rad50-Nbs (MRN) complex in Drosophila melanogaster
label: MRN complex
module_type: PROTEIN_COMPLEX
description: >-
  The MRN complex senses DNA double-strand breaks. Rad50, an SMC-like ATPase
  with a long coiled-coil, tethers DNA ends; Mre11 is a nuclease with
  3'-5' exonuclease and single-stranded endonuclease activities that starts
  resection of break ends; Nbs (Nibrin) mediates recruitment and activation of
  the ATM kinase. In Drosophila, mre11, rad50 and nbs are also required to
  prevent telomere fusions.
summary: >-
  Double-strand break sensor of Mre11 nuclease, Rad50 ATPase and Nbs that
  initiates end resection and ATM signalling.
concepts:
  - {id: GO:0030870, label: Mre11 complex}
cellular_components:
  - {id: GO:0005634, label: nucleus}
group: MRN
unit_functions:
  mre11: {id: GO:0008296, label: "3'-5'-DNA exonuclease activity"}
  rad50: {id: GO:0016887, label: ATP hydrolysis activity}
roles:
  mre11: Mre11 nuclease subunit
  rad50: Rad50 SMC-like ATPase and DNA-tethering subunit
  nbs: Nbs subunit for ATM recruitment
notes: >-
  Catalytic activities are assigned to Mre11 and Rad50 by conservation with
  the characterized yeast and human proteins. ATM (tefu) and downstream repair
  factors are outside the module.