The centromere kinetochore region

At the heart of the kinetochore is a specialized nucleosome that contains centromere protein (CENP)-A, a histone H3 homologue. Several inner kinetochore components (cyan and purple ovals) associate with kinetochores throughout the cell cycle. Many other proteins are recruited to the outer kinetochore specifically in mitosis. They provide a landing platform for the spindle-assembly checkpoint (SAC) proteins. The Ndc80/HEC1 complex seems to be directly involved in microtubule binding. Several microtubule-plus-end-binding proteins (+TIPs) are important for microtubule to kinetochore attachment. Most proteins indicated in this drawing are present at kinetochores in all metazoans.