A partial sequence of UBN1 had previously been identified during the cloning of the periplakin (PPL) gene. The UBN1 gene encodes a deduced 1,134-amino acid protein with a calculated molecular mass of 121,529 Da and a pI of 9.34.

Overexpression of tagged UBN1 cDNA constructs in keratinocytes revealed that the N terminus is essential for the nuclear localization, and that the central domain is responsible for the interaction with EB1 and for the phenotype of transfected keratinocytes similar to terminal differentiation. Cotransfection and overexpression of ubinuclein and EB1 revealed that the 2 proteins colocalize to the nucleus. In cells that were flat and appeared spread out on top of the basal cell layer, both proteins were also detected in a punctate pattern in the cytoplasm.