The ubiquitin-like domain (ULD) of about 100 amino acids is found in two protein families:

• SATB (Special AT-rich binding protein) family proteins have emerged as key regulators that integrate higher-order chromatin organization with the regulation of gene expression. SATB family chromatin organizers are involved in long-range enhancer function, extension of chromatin modifications and dynamic tethering of chromatin loops, and play diverse and important roles in regulating the dynamic equilibrium of apoptosis, cell invasion, metastasis, proliferation, angiogenesis, and immune modulation. SATB family proteins consist of ULD and CUTL (see <PDOC51983>) domains at the N terminus, a homeodomain (HD) (see <PDOC00027>) at the C terminus, and tandem CUT domains (see <PDOC51042>) in the center [1,2,3,4,5].
• The Compass family proteins defective proventriculus (dve) from Drosophila, required for the formation of the proventriculus and proximodistal patterning of the wing disc, and dve-1 from Caenorhabditis elegans, required for embryonic development and maintenance of mitochondrial morphology. They contain the ULD domain as well as two atypical HDs [4,5,6].

The ULD domain adopts an ubiquitin-like fold comprising four antiparallel β-sheets that are flanked by four α-helices (see <PDB:3TUO>). The ULD domain of SATB1 assembles into a tetramer and the tetramerization of SATB1 is essential for recognizing specific DNA sequences (such as multiple AT-rich DNA fragments) [2,3].

The profile we developed covers the entire ULD domain.