Kinetochore, which is coincident with the centromere and is a trilaminar plate situated at the primary constriction (or centromere) of the chromosome, plays an important role in chromosome movements. It is through these specialized structures called kinetochores, that the chromosomes get attached to microtubules (Fig. 8.9) and help in their movement during anaphase. Recent studies have also shown that kinetochores are sites for generation of force required for chromosome movement.
Following generalizations (based on experiments) have been made regarding kinetochore, spindle apparatus, centrosome and interactions between them : (i) At the time of spindle formation, there is an increase in phosphorylation of several proteins, (ii) Kinetochore microtubules (MTs) can both add (polymerization) and lose (depolymerization) subunits at or near the kinetochores; similarly, subunits addition (polymerization) at the centrosome-distal ends of MTs leads to elongation of continuous fibres, (iii) Kinetochores are capable of both binding to and sliding on the microtubules. (iv) During formation of spindle at prometaphase, a chromosome is under tension from both ends of the spindle, so that a centrosome directed force is acting at each kinetochore.