This is the C-terminal domain found in eukaryotic UCH37 proteins (also known as Ubiquitin carboxyl-terminal hydrolase isozyme L5, UCHL5). UCH37 is a subunit of two complexes: INO80, which performs ATP-dependent sliding of nucleosomes for transcriptional regulation and DNA repair, and the 26S proteasome, which performs ATP-dependent proteolysis of polyubiquitylated proteins in the cytosol and nucleus. Recruitment to the proteasome is mediated by the C-terminal domain of RPN13 (also known as ADRM1). Recruitment to INO80 is mediated by the N-terminal domain of NFRKB. Structural and biochemical analysis reveal that RPN13 and NFRKB make similar interactions with the UCH37 C-terminal domain but have very different interactions with the catalytic UCH domain that are activating in the case of RPN13 and highly inhibitory in the case of NFRKB [3].

1: Stabilization of an unusual salt bridge in ubiquitin by the extra C-terminal domain of the proteasome-associated deubiquitinase UCH37 as a mechanism of its exo specificity. Morrow ME, Kim MI, Ronau JA, Sheedlo MJ, White RR, Chaney J, Paul LN, Lill MA, Artavanis-Tsakonas K, Das C; Biochemistry. 2013;52:3564-3578. PMID:23617878

2: Structural characterization of human Uch37. Burgie SE, Bingman CA, Soni AB, Phillips GN Jr; Proteins. 2012;80:649-654. PMID:21953935

3: Structural basis for the activation and inhibition of the UCH37 deubiquitylase. VanderLinden RT, Hemmis CW, Schmitt B, Ndoja A, Whitby FG, Robinson H, Cohen RE, Yao T, Hill CP; Mol Cell. 2015;57:901-911. PMID:25702872