The nuclear pore complex (NPC) mediates the transport of macromolecules acrossthe nuclear envelope (NE). The NPC is composed of a relatively small number ofproteins (~30), termed nucleoporins or Nups. The vertebrate nuclear poreprotein Nup35, the ortholog of Saccharomyces cerevisiae Nup53p, is suggestedto interact with the NE membrane and to be required for nuclear morphology.The highly conserved region between vertebrate Nup35 and yeast Nup53p ispredicted to contain an RNA-recognition motif (RRM) domain.The sequences of the RRM Nup-35-type domain are highly conserved in alleucaryotes. The RRM Nup35-type domain adopts the characteristic BetaAlphaBetaBetaAlphaBeta topology of the secondary structure elements, with a four-stranded antiparallel β-sheet packed against two alpha helices. The RRM Nup35-type domain forms a homodimer and contains atypicalrinonucleoprotein (RNP) motifs, which lack the conserved residues thattypically bind RNA in canonical RRM domains. The dimer interface involves theβ-sheet surface, with its atypical RNP motifs, which is generally used tobind RNA in typical RRM domains [].This entry represents the RRM Nup35-type domain.
