It is known that nucleoporins, a family of glycoproteins with N-acetylglucosamine that are found in nuclear pore complexes, are essential for nuclear import and export. A major component of the family, p 62, was purified from a salt extract of rat liver nuclear envelopes by wheat germ agglutinin-Sepharose affinity chromatography and DEAE-anion exchange HPLC. p 62 was purified as a complex with two glycoproteins of 60 and 54 kDa. The presence of the complex was confirmed by gel filtration, glycerol density gradient centrifugation, and cross-linking experiments. The molecular ratio of the 62-, 60-, and 54-kDa components of the complex was estimated to be 1:1.1±0.2:1.7±0.3 from the intensity of Coomassie Blue staining of SDS-PAGE gels. The complex was stable against 1M NaCl, 1% Triton X-100, and 2M urea. The Stokes' radius and sedimentation coefficient of the complex are 8.0 nm and 6.7 S. The molecular mass and frictional ratio of the complex were estimated to be about 231 kDa and 2.0, respectively. p 62 and p 54 were acidic and neutral proteins, respectively, exhibiting charge heterogeneities, and p 60 was assumed to be a basic protein. p 60 tended to undergo proteolytic degradation to a 47-kDa fragment.