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BRISC complex subunit Abraxas 2 BRISC complex subunit Abraxas 2 is also known as ABRO1, FAM175B, or KIAA0157. The BRISC complex consists of BRCC36, MERIT40, BRE, and Abraxas 2, and serves cellular stress response and immune signaling functions; it specifically cleaves 'Lys-63'-linked polyubiquitin, leaving the last ubiquitin chain attached to its substrates; BRISC's catalytic subunit is the deubiquitinase (DUB) BRCC36. BRCC36 associates with pseudo-DUB protein Abraxas2, which lacks the essential Zn2+-coordinating residues required for DUB catalytic function. Higher-order association of BRCC36 and Abraxas2 into a dimer of heterodimers (superdimer) is required for BRCC36 DUB activity. In the BRISC complex, Abraxas 2 binds SHMT2a, a metabolic enzyme enabling cancer growth in hypoxic environments, which prevents the BRCC36 from binding and cleaving ubiquitin chains. BRCC36 in BRISC is activated by assembly due to interaction between Glu30 of BRCC36 and Asn164 in Abraxas 2 which structures the activation loop and positions the catalytic Glu33. The members here include Abraxas 2 domains. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",