INHIBITION OF ANAPHASE SPINDLE ELONGATION IN-VITRO BY A PEPTIDE ANTIBODY THAT RECOGNIZES KINESIN MOTOR DOMAIN

Isolated central spindles or spindles in detergent-permeabilized cells from the diatom Cylindrotheca fusiformis can undergo ATP-dependent re activation of spindle elongation in vitro. We have used a peptide anti body raised against a 10-amino add portion common to the kinesin super family motor domain to look for kinesin-like motor activity during ana phase B of mitosis. The peptide antibody localizes to central spindles . Upon ATP reactivation of spindle elongation, antigens recognized by the antibody are associated exclusively with the central spindle midzo ne where antiparallel microtubules of each half-spindle overlap. The a ntibody recognizes several polypeptides by immunoblot using isolated s pindle extracts. One of these polypeptides behaves like kinesin with r espect to nucleotide-specific binding to and release from taxol-stabil ized microtubules. Preincubation of the spindle model with the peptide antibody inhibits subsequent ATP reactivation of spindle elongation. Coincubation of the peptide antibody with peptide antigen rescues spin dle function. These results support a role for kinesin-related protein (s) in spindle elongation (anaphase B) of mitosis and suggest that one or several polypeptides that we have identified in spindle extracts m ay fulfill this function.