Ubiquitin-dependent proteolysis of cyclin D1 is associated with normal and tumour cell proliferation and survival. The best characterised member of this family is the SCF FBXO31 (Skp1-Cul1-Rbx1-FBXO31) ubiquitin ligase complex mediates genotoxic stress-induced cyclin D1 degradation [1]. FBXO31 possesses a unique substrate-binding beta barrel domain, whereas cyclin D1 binds to FBXO31 by tucking its free C-terminal carboxylate tail into an open cavity of the C-terminal FBXO31 beta-barrel. Biophysical and functional studies demonstrated that SCFFBXO31 is capable of recruiting and ubiquitinating cyclin D1 in a phosphorylation-independent manner.

1: Structural basis of the phosphorylation-independent recognition of cyclin D1 by the SCF(FBXO31) ubiquitin ligase. Li Y, Jin K, Bunker E, Zhang X, Luo X, Liu X, Hao B; Proc Natl Acad Sci U S A. 2018;115:319-324. PMID:29279382