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Human MOK2 is a DNA-binding transcriptional repressor. Previously, we identified nuclear lamin A⁄C proteins as protein partners of hsMOK2. Fur-thermore, we found that a fraction of hsMOK2 protein was associated with the nuclear matrix. We therefore suggested that hsMOK2 interactions with lamin A⁄C and the nuclear matrix may be important for its ability to repress transcription. | ỊFEBS Journal Phosphorylation-dependent binding of human transcription factor MOK2 to lamin A C Maryannick Harper Jeanne Tillit Michel Kress and Michele Ernoult-Lange CNRS-FRE2937 Institut André Lwoff Villejuif France Keywords Aurora A JLP JNK3 JSAP1 MOK2 Correspondence M. Ernoult-Lange CNRS-FRE2937 Institut André Lwoff 7 rue Guy Moquet 94801 Villejuif France Fax 33 1 49 58 33 43 Tel 33 1 49 58 33 46 E-mail ernoult@vjf.cnrs.fr Received 15 December 2008 revised 4 March 2009 accepted 31 March 2009 doi 10.1111 j.1742-4658.2009.07032.x Human MOK2 is a DNA-binding transcriptional repressor. Previously we identified nuclear lamin A C proteins as protein partners of hsMOK2. Furthermore we found that a fraction of hsMOK2 protein was associated with the nuclear matrix. We therefore suggested that hsMOK2 interactions with lamin A C and the nuclear matrix may be important for its ability to repress transcription. In this study we identify JNK-associated leucine zipper and JSAP1 scaffold proteins two members of c-Jun N-terminal kinase JNK -interacting proteins family as partners of hsMOK2. Because these results suggested that hsMOK2 could be phosphorylated we investigated the phosphorylation status of hsMOK2. We identified Ser38 and Ser129 of hsMOK2 as phosphorylation sites of JNK3 kinase and Ser46 as a phosphorylation site of Aurora A and protein kinase A. These three serine residues are located in the lamin A C-binding domain. Interestingly we were able to demonstrate that the phosphorylation of hsMOK2 interfered with its ability to bind lamin A C. The zinc-finger transcription factor MOK2 recognizes both DNA and RNA through its zinc-finger motifs 1 . This dual affinity suggests that MOK2 may play a role in transcription as well as in the post-transcriptional regulation of specific genes. We have shown that MOK2 represses expression of the interphotoreceptor retinoid-binding protein IRBP gene 2 . IRBP contains two MOK2-binding elements a complete 18-bp MOK2-binding site .