This region is found in E3 ubiquitin ligases that recognise N-recognins [1].

1: A family of mammalian E3 ubiquitin ligases that contain the UBR box motif and recognize N-degrons. Tasaki T, Mulder LC, Iwamatsu A, Lee MJ, Davydov IV, Varshavsky A, Muesing M, Kwon YT; Mol Cell Biol. 2005;25:7120-7136. PMID:16055722

2: Female lethality and apoptosis of spermatocytes in mice lacking the UBR2 ubiquitin ligase of the N-end rule pathway. Kwon YT, Xia Z, An JY, Tasaki T, Davydov IV, Seo JW, Sheng J, Xie Y, Varshavsky A; Mol Cell Biol. 2003;23:8255-8271. PMID:14585983

3: Construction and analysis of mouse strains lacking the ubiquitin ligase UBR1 (E3alpha) of the N-end rule pathway. Kwon YT, Xia Z, Davydov IV, Lecker SH, Varshavsky A; Mol Cell Biol. 2001;21:8007-8021. PMID:11689692

4: The mouse and human genes encoding the recognition component of the N-end rule pathway. Kwon YT, Reiss Y, Fried VA, Hershko A, Yoon JK, Gonda DK, Sangan P, Copeland NG, Jenkins NA, Varshavsky A; Proc Natl Acad Sci U S A. 1998;95:7898-7903. PMID:9653112