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BMC Cell Biol. 2008 Jul 21;9:39. doi: 10.1186/1471-2121-9-39.

Importin alpha binding and nuclear localization of PARP-2 is dependent on lysine 36, which is located within a predicted classical NLS.

Author information

1
Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. haennis@vetbio.uzh.ch

Abstract

BACKGROUND:

The enzymes responsible for the synthesis of poly-ADP-ribose are named poly-ADP-ribose polymerases (PARP). PARP-2 is a nuclear protein, which regulates a variety of cellular functions that are mainly controlled by protein-protein interactions. A previously described non-conventional bipartite nuclear localization sequence (NLS) lies in the amino-terminal DNA binding domain of PARP-2 between amino acids 1-69; however, this targeting sequence has not been experimentally examined or validated.

RESULTS:

Using a site-directed mutagenesis approach, we found that lysines 19 and 20, located within a previously described bipartite NLS, are not required for nuclear localization of PARP-2. In contrast, lysine 36, which is located within a predicted classical monopartite NLS, was required for PARP-2 nuclear localization. While wild type PARP-2 interacted with importin alpha3 and to a very weak extent with importin alpha1 and importin alpha5, the mutant PARP-2 (K36R) did not interact with importin alpha3, providing a molecular explanation why PARP-2 (K36R) is not targeted to the nucleus.

CONCLUSION:

Our results provide strong evidence that lysine 36 of PARP-2 is a critical residue for proper nuclear targeting of PARP-2 and consequently for the execution of its biological functions.

PMID:
18644123
PMCID:
PMC2496901
DOI:
10.1186/1471-2121-9-39
[Indexed for MEDLINE]
Free PMC Article

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