Recruitment of substituted forms of human ERH to nuclear speckles and replication foci in HeLa cells visualized by confocal microscopy.

<p>EGFP-tagged substituted forms of ERH expressed alone (top) or coexpressed with mCherry-tagged human PDIP46/SKAR (middle) or mCherry-tagged human Ciz1 (bottom). <b>A</b>. ERH T18A S24A localizes to the nucleus and is recruited both to nuclear speckles and to replication foci similarly to wild-type ERH. <b>B</b>. ERH H3A Q9A is present not only in the nucleus but also in the cytoplasm, shows diminished recruitment to nuclear speckles but still accumulates in replication foci. <b>C</b>. ERH E37A T51A localizes partly to the cytoplasm, is recruited to nuclear speckles, and shows very week accumulation in replication foci. <b>D</b>. ERH H3A Q9A E37A T51A is also present in the cytoplasm and recruited neither to nuclear speckles nor to replication foci.</p

GST pull-down assay with substituted forms of human ERH.

<p>Indicated FLAG-tagged ERH forms incubated with either GST-tagged fragment L7 of human PDIP46/SKAR (GST-PDIP46/SKAR[L7]) or GST-tagged fragment B of human Ciz1 (GST-Ciz1[B]) and detected by western blotting with anti-FLAG antibody followed by enhanced chemiluminescence reaction. PDIP46/SKAR does not interact with ERH H3A Q9A or ERH H3A Q9A E37A T51A, and Ciz1 does not interact with ERH E37A T51A or ERH H3A Q9A E37A T51A.</p

Amino acid residues of human ERH critical for its recruitment to nuclear speckles and replication foci.

<p>Three-dimensional structure of a monomer of ERH was produced by UCSF Chimera package using coordinates from Protein Data Bank (2nmlA) [30]. Four β strands (β1, β2, β3 and β4), three α helices (α1, α2 and α3) and the N- and C-termini are indicated. Critical residues are shown with their side chains in color and are labeled using a single-letter code and position number in the polypeptide chain. Residues involved in the recruitment to nuclear speckles (in red) and replication foci (in green) are situated on the β sheet and near the loop between helices α1 and α2, respectively.</p