Functional nuclear pores reconstituted with beta 1-4 galactose-modified O-linked N-acetylglucosamine glycoproteins.

Abstract

Nuclear pore proteins bearing O-linked N-acetylglucosamine (GlcNAc) are involved in nuclear transport, although a role for their glycosylation is not established. Xenopus egg extracts capable of reforming functional nuclei in vitro yielded nuclei with impaired transport and reduced nuclear pore density when depleted of wheat germ agglutinin-binding proteins. Many of the nuclear pores remaining in wheat germ agglutinin-depleted nuclei showed a striking loss of internal structure. Nuclear transport and normal nuclear pore structure were restored by the addition of nuclear pore glycoproteins from rat liver or Xenopus eggs. Glycoproteins modified by the addition of galactose to O-linked GlcNAc were also competent for assembling normal nuclear pores and restoring nuclear transport. Aphidicolin-sensitive DNA synthesis was unaffected by the removal or modification of O-linked GlcNAc glycoproteins. These data argue against a requirement for a lectin-like recognition of O-linked GlcNAc glycoproteins in nuclear pore assembly, nuclear transport, or DNA synthesis.