Overlapping signals for protein degradation and nuclear localization define a role for intrinsic RAG-2 nuclear uptake in dividing cells

Ashley E. Ross, Milena Vuica, Stephen Desiderio

Research output: Contribution to journalArticle

Abstract

Expression of the recombinase proteins RAG-1 and RAG-2 is discordant: while RAG-1 is relatively long lived, RAG-2 is degraded periodically at the G1-S transition. Destruction of RAG-2 is mediated by a conserved interval in the recombination-dispensable region. The need for RAG-2 to reaccumulate in the nucleus at each cell division suggested the existence of an intrinsic RAG-2 nuclear localization signal (NLS). RAG-1 or RAG-2, expressed individually, is a nuclear protein. A screen for proteins that bind the recombination-dispensable region of RAG-2 identified the nuclear transport protein Importin 5. Mutation of residues 499 to 508 in RAG-2 abolished Importin 5 binding, nuclear accumulation, and periodic degradation of RAG-2. The Importin 5 binding site overlaps an NLS, defined by mutagenesis. RAG-1 rescued the localization of degradation-defective, RAG-2 NLS mutants; this required an intact RAG-1 NLS. Mutations in RAG-2 that abolish intrinsic nuclear accumulation but spare periodic degradation impaired recombination in cycling cells; induction of quiescence restored recombination to wild-type levels. Recombination defects were correlated with a cell cycle-dependent defect in the ability of RAG-1 to rescue localization of the RAG-2 mutants. These results suggest that the intrinsic RAG-2 NLS functions in the nuclear uptake of RAG-2 following its reexpression in cycling cells.

Original languageEnglish (US)
Pages (from-to)5308-5319
Number of pages12
JournalMolecular and cellular biology
Volume23
Issue number15
DOIs
StatePublished - Aug 1 2003

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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