May be a substrate targeting component of a cullin-RING-based E3 ubiquitin-protein ligase complex RTT101(MMS1-ESC2). Involved in HMR and telomere silencing via the recruitment or stabilizing of the SIR (silent information regulators) complex. Component of a cullin-RING ligase (CRL)-like complex composed of at least the cullin RTT101, a linker protein MMS1, and the potential substrate receptor ESC2. Interacts with RTT101 and MMS1. Interacts with SIR2. The 2 SUMO-like regions, although related to ubiquitin domains lack the conserved acceptor Gly residue in position 456. Present with 1890 molecules/cell in log phase SD medium.