Xenopus Ran-binding protein 1: molecular interactions and effects on nuclear assembly in Xenopus egg extracts.
AffiliationZeneca Laboratory of Molecular and Cellular Biology, School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK.
MetadataShow full item record
AbstractRan is a nuclear GTPase implicated in nucleocytoplasmic transport, the maintenance of nuclear structure, mRNA processing, and cell cycle regulation. By two-hybrid interaction in yeast, we have identified a Xenopus homologue of Ran-binding protein 1 (RanBP1). Xenopus RanBP1 interacts specifically with the GTP-bound form of Ran and forms complexes in Xenopus egg extracts with Ran, importin-beta/karyopherin-beta and importin-alpha/karyopherin-alpha, but not p10, p120/RanBP7, RanBP2 or other nucleoporins. These complexes may play roles in the recycling of Ran and importins/karyopherins during nucleocytoplasmic transport. Increased concentrations of RanBP1 stabilise an interaction between Ran and RCC1 in egg extracts, inhibiting the exchange activity of RCC1 towards Ran. Under these conditions, the assembly of nuclei from chromatin is dramatically affected: the nuclei do not assemble a lamina and become very small with homogeneously condensed chromatin. They fail to actively import proteins and do not undergo DNA replication. By field emission in-lens scanning electron microscopy, we show that these nuclei have an intact nuclear envelope containing pore complexes, but the envelope is highly convoluted. However, RanBP1 does not directly inhibit nuclear protein import in assembled nuclei. These results suggest that RCC1 and/or Ran have a function early in nuclear assembly that is disrupted by RanBP1.
CitationXenopus Ran-binding protein 1: molecular interactions and effects on nuclear assembly in Xenopus egg extracts. 1997, 110 ( Pt 24):3019-30 J. Cell. Sci.
JournalJournal of Cell Science
- The role of the ran GTPase in nuclear assembly and DNA replication: characterisation of the effects of Ran mutants.
- Authors: Hughes M, Zhang C, Avis JM, Hutchison CJ, Clarke PR
- Issue date: 1998 Oct
- Ran-binding protein 1 (RanBP1) forms a ternary complex with Ran and karyopherin beta and reduces Ran GTPase-activating protein (RanGAP) inhibition by karyopherin beta.
- Authors: Lounsbury KM, Macara IG
- Issue date: 1997 Jan 3
- A mutant form of the Ran/TC4 protein disrupts nuclear function in Xenopus laevis egg extracts by inhibiting the RCC1 protein, a regulator of chromosome condensation.
- Authors: Dasso M, Seki T, Azuma Y, Ohba T, Nishimoto T
- Issue date: 1994 Dec 1
- XMog1, a nuclear ran-binding protein in Xenopus, is a functional homologue of Schizosaccharomyces pombe mog1p that co-operates with RanBP1 to control generation of Ran-GTP.
- Authors: Nicolás FJ, Moore WJ, Zhang C, Clarke PR
- Issue date: 2001 Aug
- Random mutagenesis and functional analysis of the Ran-binding protein, RanBP1.
- Authors: Petersen C, Orem N, Trueheart J, Thorner JW, Macara IG
- Issue date: 2000 Feb 11