Nucleolar transcription factor/upstream binding factor contains six HMG box domains. This is the fifth HMG box domain in these proteins. This domain has lost DNA-binding ability [1].

1: Solution structure and DNA binding property of the fifth HMG box domain in comparison with the first HMG box domain in human upstream binding factor. Yang W, Xu Y, Wu J, Zeng W, Shi Y; Biochemistry. 2003;42:1930-1938. PMID:12590579