Core histones organize DNA in the nucleus. Histones are synthesized in the cytoplasm and are be transported by to the nucleus by Karyopherin nuclear transport receptors. In the cytoplasm, histones also bind to histone chaperones, which often accompanies them into the nucleus. The core histone dimer H2A-H2B binds histone chaperone Nap1 in the cytoplasm. In S. cerevisiae, the karyopherin Kap114 imports both H2A-H2B and Nap1, separately and together, into the nucleus. In the nucleus, both Nap1 and Kap114 participate in nucleosome assembly. This proposal focuses on structure determination of the Kap114 complexes with Nap1 and H2A-H2B that form in the cytoplasm and the nucleus, to reveal the mechanisms of how Kap114 recognizes both proteins into the cytoplasm and how the proteins are released from Kap114 in the nucleus.