DIRECT INTERACTION OF NUCLEOPORIN P62 WITH MESSENGER-RNA DURING ITS EXPORT FROM THE NUCLEUS

Primary transcripts in eukaryotic cells undergo several processing ste ps within the nucleus, and resulting mature RNA molecules are selectiv ely exported to the cytoplasm. Nucleo-cytoplasmic mRNA transport is an active process that likely involves RNA-protein interactions. To iden tify specific RNA-binding proteins, we designed a novel approach, whic h allows the analysis of interactions between mRNAs and proteins along the transport pathway. The method consists of inducing in vivo a cova lent binding between nuclear proteins and microinjected mRNAs. Using s uch a procedure, we were able to detect a direct interaction between n ucleoporin p62 with mRNA during export. The formation of the mRNA-p62 complex was inhibited by wheat-germ agglutinin, an inhibitor of mRNA e xport. Antibodies directed against p62 caused a substantial reduction in the rate of mRNA export from the nucleus.