An analysis of the protein interactions involved in classical nuclear import

Abstract

Every aspect of eukaryotic cellular life involves the trafficking of proteins and other biomolecules through the nuclear membrane for the purposes of bringing feedback to or information from the nucleus. Many proteins larger than 40 kDa must be actively imported into the nucleus by a process termed classical nuclear import. This process is vital to almost every aspect of cellular function. The primary binding event of the translocation process is the recognition, by the cytosolic receptor karyopherin [], of a small passport sequence, on the surface of the cargo protein, termed a Nuclear Localization Sequence (NLS). The structural and physical properties of this passport sequence and its interaction with the receptor were analyzed using biochemical, biophysical, synthetic, and biological methods. Two different, complimentary assays were developed and utilized in the analysis of a variety of rationally designed passport mimics intended to probe the requirements of natural passports.