Fig. 4.

TAP-CBX4 purification from HeLa cells reveals CBX4 oligomerization. A, Schematic representation of the human CBX4 locus. Two transcripts are generated from the CBX4 locus by an alternative splicing event. Exons are drawn as boxes. Dark boxes correspond to coding regions, whereas white boxes correspond to untranslated regions. The part of exon 5 spliced out in CBX4_isoform 2, and specific to CBX4_isoform 1 is shown in black. B, CBX4_isoform 2 protein sequence used for protein complex purifications by TAP. The identified peptides are indicated as black boxes on the protein sequence. C, CBX4_isoform 1 protein sequence. Part of the sequence specific to CBX4_isoform 1 and spliced out in CBX4_isoform 2 is in italic. The identified peptides specific to CBX4_isoform 1 are indicated as gray boxes on the protein sequence. A putative 14-3-3 binding motif is shown in a white box. Underlined serine is mutated into an alanine in the CBX4[S164A] mutant version.