Identification and functional characterization of a bipartite nuclear localization signal in ANKRD11

ANKRD11 gene encodes for the large nuclear protein essential for multiple system development including the nervous system. However, the molecular basis for the proper nuclear localization of ANKRD11 has not yet been elucidated. In this study, we have identified a functional bipartite nuclear localization signal (bNLS) between residues 53 and 87 of ANKRD11. Using biochemical approaches, we discovered two major binding sites in this bipartite NLS for Importin α1. Through site-directed mutagenesis and functional analysis, we further found that this bipartite NLS is sufficient for nuclear import of overexpressing GFP in HeLa cells and necessary for nuclear localization of ANKRD11. Importantly, our study provides a possible pathogenic mechanism for certain clinical variants located within the bipartite nuclear localization signal of ANKRD11.