Berlin 2001 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 2: Single Molecule Spectroscopy

CPP 2.1: Talk

Tuesday, April 3, 2001, 15:45–16:05, 110

SINGLE PROTEIN MOLECULES BEING TRANSLOCATED BY THE NUCLEAR PORE COMPLEX — •Ulrich Kubitscheck, Dirk Schmalz, Thorsten Kues, and Reiner Peters — Institut für Medizinische Physik und Biophysik, Westfälische Wilhelms-Universität Münster

The nuclear import of proteins plays a central role in the complex intracellular transport machinery. The nuclear uptake of karyophilic proteins occurs via the nuclear pore complex (NPC), a supramolecular protein transporter located in the nuclear envelope with a diameter of 120 nm and a length of app. 70 nm. We now succeeded for the first time in observing the attachment of single molecules of import cargo to the NPC, and to observe the single molecule translocation process with an accuracy of some tens of nanometers on a millisecond time scale using dedicated dual color laser microscopic methods. As transport substrate we employed bovine serum albumin (BSA), which carried a nuclear localization signal and was fluorescently labeled by the red dye Alexa 633. The NPC were visualized by means of green fluorescent proteins that were genetically engineered to an intrinsic NPC protein, POM121. From our experiments we gain information on the dynamic aspects of the import process for the first time on a single molecule level.