Structure and function of the outer kinetochore.

The outer kinetochore's KMN complex is essential for microtubule binding and mitotic checkpoint regulation, with high-precision control achieved by a few KMN units per microtubule.

• Why it matters: Understanding how the kinetochore ensures accurate chromosome segregation is critical for insights into cell division errors and related diseases. The specific mechanisms of the outer kinetochore's regulation remain unclear, limiting potential therapeutic targets.
• What they did: The study combines live-cell imaging, biochemical reconstitution, and high-resolution structural analyses to investigate how a limited number of KMN complexes coordinate multiple functions at each microtubule-binding site.
• The result: Findings reveal that a small number of KMN complexes can precisely regulate microtubule attachment and spindle checkpoint signaling, enabling accurate chromosome segregation and advancing knowledge of kinetochore function.