The N-terminal domain is a fragment that binds proteins and anchors topoisomerase I in the nucleolus. As a separate polypeptide, it translocates from the nucleolus to nucleoplasm upon camptothecin treatment. In this paper, we show that the translocation depends on the short fragment of the domain (residues from 1 to 67). We also present a list of proteins that specifically bind to the fragment responsible for translocation. (c) 2007 Elsevier Inc. All rights reserved.