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Covalent modification of the homeodomain-interacting protein kinase 2 (HIPK2) by the ubiquitin-like protein SUMO-1.

Posttranslational modifications such as ubiquitination and phosphorylation play an important role in the regulation of cellular protein function. Homeodomain-interacting protein kinase 2 (HIPK2) is a member of the recently identified family of nuclear protein kinases that act as corepressors for homeodomain transcription factors. Here, we show that HIPK2 is regulated by a ubiquitin-like protein, SUMO-1. We demonstrate that HIPK2 localizes to nuclear speckles (dots) by means of a speckle-retention signal. This speckle-retention signal contains a domain that interacts with a mouse ubiquitin-like protein conjugating (E2) enzyme, mUBC9. In cultured cells, HIPK2 is covalently modified by SUMO-1, and the SUMO-1 modification of HIPK2 correlates with its localization to nuclear speckles (dots). Thus, our results provide firm evidence that the nuclear protein kinase HIPK2 can be covalently modified by SUMO-1, which directs its localization to nuclear speckles (dots).

Pubmed ID: 10535925


  • Kim YH
  • Choi CY
  • Kim Y


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

October 26, 1999

Associated Grants


Mesh Terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Carrier Proteins
  • Cell Line
  • DNA Primers
  • Humans
  • Immunohistochemistry
  • Ligases
  • Mice
  • Molecular Sequence Data
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • SUMO-1 Protein
  • Sequence Homology, Amino Acid
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitins