The arabidopsis histone methyltransferase SUVR4 binds ubiquitin via a domain with a four-helix bundle structure.
Rahman MA, Kristiansen PE, Veiseth SV, Andersen JT, Yap KL, Zhou MM, Sandlie I, Thorstensen T, Aalen RB. Biochemistry. 2014 Apr 8; 53(13):2091-100. Epub 2014 Mar 25.