Zation of CaM KMTCharacterization of CaM KMTFigure 4. CaM KMT interacts with Hsp90. (A) Lysates of HEK293 cells transiently transfected with FLAG- CaM KMT or FLAG were immunoprecipitated with anti-FLAG antibody. The precipitated proteins were subjected to SDS-PAGE and then Coomassie stained. Molecular mass markers in kDa are indicated on the left. The band of approximately 90 kDa (shown with the asterisk) was excised from the gel, and analyzed by mass spectrometry. The heavy chains of the antibodies ,50 kDa, two nonspecific bound proteins about 70 kDa and FLAG-CaM KMT immunoprecipitated protein were also observed. (B) Alignment of the protein sequences Hsp90a and HSP90b. The bold stretches of amino acids (26 of the protein sequence) represent peptide sequences as identified by mass spectrometry in the NCBI data bank matching Hsp90a and Hsp90b. Diverse amino acids in Hsp90a and Hsp90b, present in the sequenced peptides and enable to distinguish between the isoforms (shown in red). (C) CaM KMT and Hsp90 proteins immunoprecipitate each other.HEK293 cells were transiently transfected with Myc-CaM KMT or an empty Myc vector and 48 h after the transfection, equal protein amounts of whole cell lysates were immunoprecipitated using an anti-Myc (left), MedChemExpress SPI1005 anti-Hsp90 (right) and mock IgG antibody (left) as a negative control. The immunoprecipitates were subjected to the Western blot analysis using anti-Myc and anti-Hsp90 antibody as indicated. Equal protein amounts in the immunoprecipitation assays were demonstrated by analysis of 1 input. These experiments were repeated three times with identical results. doi:10.1371/journal.pone.0052425.gchromatin protein 1 (HP1) [34,35]. The significance of the automethylation is not known, for Dnmt3a it was suggested to be either a regulatory mechanism which could inactivate unused DNA methyltransferases in the cell, or Met-Enkephalin site simply be an aberrant side reaction caused by the high methyl group transfer potential of AdoMet [36]. Our analysis of the subcellular localization of CaM KMT within the cell showed both cytoplasmic and nuclear localization. Taking together these observations suggests CaM KMT activity probably takes place in both compartments. The distribution of CaM KMT in the nucleus and the cytoplasm seems equal 24195657 in all cells, suggesting that the shuttling is not a cell cycle dependent event. However, the purpose and the mechanism of the shuttling into the nucleus remains to be further investigated. Intracellular distribution of calmodulin was also found to be both nuclear and cytoplasmic. Little is known about how the subcellular localization of calmodulin is regulated, a process that, by itself, could regulate calmodulin functions [37]. Calmodulin is the major calcium sensor in neurons when present in the cytoplasm [38]. While in the nucleus, calmodulin binds to some co-transcription factors, likeBAF-57, a protein member of a complex involved in the repression of neuronal specific genes [39]. The mental retardation in the patients lacking CaM KMT may suggest an important role for CaM KMT in neuron functions. Since in the 2p21 deletion syndrome patients we previously reported reduced activity of mitochondrial respiratory complexes, except complex II [1], it was possible that CaM KMT will have a mitochondrial localization (we have tested subcellular expression of all other genes deleted in the 2p21 deletion syndrome and none localizes to the mitochondria, not reported). It could localize similar to C20orf7, a.Zation of CaM KMTCharacterization of CaM KMTFigure 4. CaM KMT interacts with Hsp90. (A) Lysates of HEK293 cells transiently transfected with FLAG- CaM KMT or FLAG were immunoprecipitated with anti-FLAG antibody. The precipitated proteins were subjected to SDS-PAGE and then Coomassie stained. Molecular mass markers in kDa are indicated on the left. The band of approximately 90 kDa (shown with the asterisk) was excised from the gel, and analyzed by mass spectrometry. The heavy chains of the antibodies ,50 kDa, two nonspecific bound proteins about 70 kDa and FLAG-CaM KMT immunoprecipitated protein were also observed. (B) Alignment of the protein sequences Hsp90a and HSP90b. The bold stretches of amino acids (26 of the protein sequence) represent peptide sequences as identified by mass spectrometry in the NCBI data bank matching Hsp90a and Hsp90b. Diverse amino acids in Hsp90a and Hsp90b, present in the sequenced peptides and enable to distinguish between the isoforms (shown in red). (C) CaM KMT and Hsp90 proteins immunoprecipitate each other.HEK293 cells were transiently transfected with Myc-CaM KMT or an empty Myc vector and 48 h after the transfection, equal protein amounts of whole cell lysates were immunoprecipitated using an anti-Myc (left), anti-Hsp90 (right) and mock IgG antibody (left) as a negative control. The immunoprecipitates were subjected to the Western blot analysis using anti-Myc and anti-Hsp90 antibody as indicated. Equal protein amounts in the immunoprecipitation assays were demonstrated by analysis of 1 input. These experiments were repeated three times with identical results. doi:10.1371/journal.pone.0052425.gchromatin protein 1 (HP1) [34,35]. The significance of the automethylation is not known, for Dnmt3a it was suggested to be either a regulatory mechanism which could inactivate unused DNA methyltransferases in the cell, or simply be an aberrant side reaction caused by the high methyl group transfer potential of AdoMet [36]. Our analysis of the subcellular localization of CaM KMT within the cell showed both cytoplasmic and nuclear localization. Taking together these observations suggests CaM KMT activity probably takes place in both compartments. The distribution of CaM KMT in the nucleus and the cytoplasm seems equal 24195657 in all cells, suggesting that the shuttling is not a cell cycle dependent event. However, the purpose and the mechanism of the shuttling into the nucleus remains to be further investigated. Intracellular distribution of calmodulin was also found to be both nuclear and cytoplasmic. Little is known about how the subcellular localization of calmodulin is regulated, a process that, by itself, could regulate calmodulin functions [37]. Calmodulin is the major calcium sensor in neurons when present in the cytoplasm [38]. While in the nucleus, calmodulin binds to some co-transcription factors, likeBAF-57, a protein member of a complex involved in the repression of neuronal specific genes [39]. The mental retardation in the patients lacking CaM KMT may suggest an important role for CaM KMT in neuron functions. Since in the 2p21 deletion syndrome patients we previously reported reduced activity of mitochondrial respiratory complexes, except complex II [1], it was possible that CaM KMT will have a mitochondrial localization (we have tested subcellular expression of all other genes deleted in the 2p21 deletion syndrome and none localizes to the mitochondria, not reported). It could localize similar to C20orf7, a.
