Although many view the kinetochore as a cell "organelle" involved in cell division (mitosis), it is really a macromolecular assembly since it lacks a surrounding membrane.  Kinetochores reside on the surface of the centromeric region, one of which is associated with each chromosome.  To date over 40 different proteins have been identified at the kinetochore, some of which are permanent components while some are transient.  As structures go it is not particularly attractive, and its appearance does not even hint at its function.  Indeed, until 10 years ago many workers viewed the kinetochore simply as a passive handle that attaches the chromosome to the mitotic spindle during cell division.  However, it is now clear that this complex and dynamic macromolecular assembly is an active participant in several critical processes.

The kinetochore does, indeed, attach the chromosome to the mitotic spindle-and the back-to-back positioning of "sister" kinetochores on the centromere of a replicated chromosome helps ensure the fidelity of chromosome distribution.  However, rather than being just a handle on a bag of genes, in vertebrates the kinetochore produces most of the force for chromosome motion.

In addition to its role in force production, the kinetochore is a central player in a cell cycle checkpoint control that has evolved to ensure a high fidelity of chromosome.  Here it functions to prevent chromatid separation, and exit from mitosis, until all of the chromosomes are properly positioned on the spindle.

In my talk I will discuss the history of the kinetochore, and our current understanding of how it executes its primary functions during cell division.