XKLP1, A CHROMOSOMAL XENOPUS KINESIN-LIKE PROTEIN ESSENTIAL FOR SPINDLE ORGANIZATION AND CHROMOSOME POSITIONING

Xklp1 is a novel Xenopus kinesin-like protein with a motor domain at t he amino terminus, nuclear localisation sequences in the stalk, and a putative zinc fingerlike sequence in the tail. It is nuclear during in terphase and chromosomal during mitosis. During late anaphase, a fract ion of the protein relocalizes to the spindle interzone and accumulate s in the midbody during telophase. Depletion of Xklp1 protein by antis ense oligo knockout in oocytes leads to defective mitosis during the f irst cell cycles following fertilization. The bipolarity of spindles a ssembled in vitro in the presence of anti-Xklp1 antibodies is unstable , and the chromosomes fail to congress on the metaphase plate.