During DNA replication, histones synthesised in the cytoplasm must be imported into the nucleusfor the formation of nucleosomes on newly replicated DNA. While core histones are transportedby monomeric importers, members of the importinß superfamily, linker histone H1 is anexception and requires formation of a heterodimeric receptor consisting of importinß andimportin7. No structural information is available for any importin:histone complex. The mainobjective of this proposal is to crystallize and solve the three-dimensional structure of theternary importinß:importin7:Histone1 complex using modern X-ray crystallography and cryoelectron microscopy methods. The structure will provide a detailed insight into the interactionnetwork of these proteins, reveal the mechanism of their recognition and explain how Imp7 isregulated by Impß.