890475.fig.005
Figure 5: Schematic showing possible interactions of Zip1 with the meiotic kinetochore. The kinetochore protein Ndc80 is sumoylated [37, 38]. Zip1 is recruited by its direct physical interactions with Nuf2 (and/or Spc24, not shown) of the Ndc80 complex (e.g., [39, 40]) and then associates by its SUMO binding motif [12] with Ndc80-SUMO. Alternately, Zip1 may be recruited by its binding with Ndc80-SUMO, which then facilitates its interaction with other components of the Ndc80 complex. Since the putative SBM (residues 853–863 [13]) was not present in the Zip1 fragment used in the two hybrid screens [39], the second scenario is less likely. Interaction between the kinetochore-bound Zip1 promotes centromere coupling. Similar protein-protein interactions may also tether the two sister kinetochores in meiosis [41]. N and C represent the –NH2 and –COOH termini of Zip1. Yellow star represents the approximate location of SBM in Zip1. Chromosome arms are not shown.