ROLE OF DIFFERENT DOMAINS IN THE SELF-ASSOCIATION OF RAT NUCLEOPORIN P62

We have expressed rat nucleoporin p62 cDNA in Escherichia coli to obta in material for structural and self-association studies. Electron micr oscopy and circular dichroism spectroscopy are consistent with a rod-s haped molecule with an a-helical coiled-coil domain at its C terminus and a cross-beta structure at its N terminus, separated by a threonine -rich linker, which has a less-defined secondary structure. Electron m icroscopy and the solubility properties of fragments produced using th rombin and CNBr digestion indicate that p62 molecules associate to for m linear chains and that a small region near the C terminus is an impo rtant determinant of assembly. This association may have important con sequences for pore structure and function; for example, one way p62 co uld associate would be to form rings in nuclear pores that could funct ion like barrel hoops.,