Structural variety among the kinetochore–MT interfaces studied here. (A) Diagram of a mammalian chromosome (purple) and its kinetochore (K; orange disk) interacting with KMTs (dark green), which connect it with a spindle pole (yellow disk). KMT numbers are from McEwen et al. (1998a). Spindles also contain MTs that do not encounter kinetochores (non-KMTs; light green). (B) 4-nm slice from a tomogram of a kinetochore from a metaphase NRK cell. (C–F) Diagrams of the kinetochores analyzed in this paper. Images are colored as in A; the structures and numbers indicated are based on this paper, Figs. S1–S4.