CENP-E forms a link between attachment of spindle microtubules to kinetochores and the mitotic checkpoint

Here we show that suppression of synthesis of the microtubule motor CENP-E (centromere-associated protein E), a component of the kinetochore corona fi bres of mammalian centromeres, yields chromosomes that are chronically mono -orientated, with spindles that are flattened along the plane of the substr ate. Despite apparently normal microtubule numbers and the continued presen ce at kinetochores of other microtubule motors, spindle poles fragment in t he absence of CENP-E, which implicates this protein in delivery of componen ts from kinetochores to poles. CENP-E represents a link between attachment of spindle microtubules and the mitotic checkpoint signalling cascade, as d epletion of this motor leads to profound checkpoint activation, whereas imm unoprecipitation reveals a nearly stoichiometric association of CENP-E with the checkpoint kinase BubR1 during mitosis.