A component of the interphase cytoskeleton is cyclically recruited into spindle poles during mitosis

During the transition from interphase to mitosis, proteins are recruited into forming spindle poles [Leslie, Cell Motil. Cytoskeleton 16:225-228, 1990]. Antibodies which recognize these recruited components clearly label spindle poles during mitosis but the location and character of such proteins during interphase remain a mystery. Competition assays using an antibody to a recruited spindle pole protein show that in its disperse form the spindle pole protein is a highly insoluble component of the cytoskeleton which is dispersed to such an extent during interphase that it is difficult to identify by immunolocalization. The function of recruited spindle pole proteins is unknown but the aggregation/dispersion cycle and the antigen are highly conserved, appearing in sea urchin embryos and tissue culture cells.