MITOTIC REGULATION OF MICROTUBULE CROSS-LINKING ACTIVITY OF CENP-E KINETOCHORE PROTEIN

CENP-E is a kinesin-like protein that is transiently bound to kinetochores during early mitosis, becomes redistributed to the spindle midzone at anaphase, and is degraded after cytokinesis. At anaphase, CENP-E may cross-link the interdigitating microtubules in the spindle midzone through a motor-like binding site at the amino terminus and a 99-amino acid carboxyl-terminal domain that bound microtubules in a distinct manner. Phosphorylation of the carboxyl terminus by the mitotic kinase maturation promoting factor (MPF) inhibited microtubule-binding activity before anaphase. Thus, MPF suppresses the microtubule cross-linking activity of CENP-E until anaphase, when its activity is lost.