Mov34/MPN/PAD-1 family: BRCC36, a subunit of BRCA1-A complex
BRCC36 (BRCA1-A complex subunit BRCC36; BRCA1/BRCA2-containing complex subunit 36; BRCA1/BRCA2-containing complex subunit 3; BRCC3; BRISC complex subunit BRCC36; BRCC36 isopeptidase complex; Lys-63-specific deubiquitinase BRCC36) and BRCC36-like domains are members of JAMM/MPN+ deubiquitinases (DUBs), possibly with Zn2+-dependent ubiquitin isopeptidase activity. BRCC36 is part of the BRCA1/BRCA2/BARD1-containing nuclear complex that displays an E3 ubiquitin ligase activity. It is targeted to DNA damage foci after irradiation; RAP80 recruits the Abraxas-BRCC36-BRCA1-BARD1 complex to DNA double strand breaks (DSBs) for DNA repair through specific recognition of Lys 63-linked polyubiquitinated proteins by its tandem ubiquitin-interacting motifs. A new protein, MERIT40 (mediator of RAP80 interactions and targeting 40 kDa), also named NBA1 (new component of the BRCA1 A complex), exists in the same BRCA1-containing complex and is essential for the integrity of the complex. There are studies suggesting that MERIT40/NBA1 ties BRCA1 complex integrity, DSB recognition, and ubiquitin chain activities to the DNA damage response. It has also been shown that BRCA1-containing complex resembles the lid complex of the 26S proteasome.