Kinetochore- and microtubule-binding protein that plays a key role in spindle assembly. Znf207/BuGZ is mainly composed of disordered low-complexity regions and undergoes phase transition or coacervation to form temperature-dependent liquid droplets. Coacervation promotes microtubule bundling and concentrates tubulin, promoting microtubule polymerization and assembly of spindle and spindle matrix by concentrating its building blocks. Interacts (via GLEBS region) with bub3. Localizes primarily to the nucleus in interphase, concentrates at kinetochores prior to nuclear envelope breakdown and during early prometaphase, and disappears from kinetochores upon microtubule-binding. The GLEBS region mediates interaction with bub3. Mainly composed of disordered low-complexity regions outside of the C2H2-type zinc fingers. Coacervation depends on hydrophobic and aromatic Phe and Tyr in the disordered low-complexity region, that may promote coacervation by forming intermolecular hydrophobic interactions. The microtubule-binding region is required for efficient loading of bub3 onto kinetochores and proper mitosis.