ULD is an N-terminal oligomerisation domain of SATB or special AT-rich sequence-binding proteins. SATBs are global chromatin organisers and regulators of gene expression that are essential for T-cell development, breast cancer tumour growth and metastasis. SATBs assemble into a tetramer via the ULD domain, and the tetramerisation of SATBs are essential for recognising specific DNA sequences (such as multiple AT-rich DNA fragments). Thus, SATBs may regulate gene expression directly by binding to various promoters and upstream regions and thereby influencing promoter activity [1].

1: The structural basis for the oligomerization of the N-terminal domain of SATB1. Wang Z, Yang X, Chu X, Zhang J, Zhou H, Shen Y, Long J; Nucleic Acids Res. 2012;40:4193-4202. PMID:22241778