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. 2008 Feb 20;3(2):e1617. doi: 10.1371/journal.pone.0001617

Figure 4. Ybp2 associates with CEN DNA in an Ndc10-dependent manner.

Figure 4

(A and B) Anti-myc chromatin immunoprecipitation (ChIP) assays were performed from log-phase cells at 30°C (A) or 25°C (B). Total lysate (T, 1/800 of the total) and coimmunoprecipitated DNA (IP, 1/10 of the total) were analyzed by PCR with primers specific to centromeric regions of chromosome I and XVI and to a noncentromeric region (PGK1) as a control for binding specificity. The myc-tagged Okp1 strain was used as positive control. For the quantification of CEN1 and CEN16, aliquots of the total lysate (2/25 of the total) and IP fraction (2/5 of the total) were loaded on an 8% acrylamide gel. Arbitrary number is defined as the ratio of the amount of coprecipitated DNA to the amount of input DNA. Intensity of the total lysate is defined as 1 in each strain. The yeast strains used were (A) untagged (YPH499), Ybp2-myc (Y1689), and Okp1-myc (Y1707); and (B) untagged (YPH499), Ybp2-myc (Y1689), Ybp2-myc ndc10-1 (Y1838), and Okp1-myc (Y1707). (C) A model of the role of Ybp2 in the central kinetochore. Ybp2 interacts strongly with proteins in the COMA and Ndc80 complexes (shown in red) but not as well with those in the MIND complex and other kinetochore proteins (shown in brown). We propose that Ybp2 is localized to bridge the COMA and Ndc80 complexes onto the centromeric nucleosome.