The Saccharomyces cerevisiae Fin1 protein forms cell cycle-specific
filaments between spindle pole bodies.
Martijn J van Hemert, H. Yde Steensma, G. Paul H. van Heusden
Inst. Molecular Plant Sciences, Leiden University, Wassenaarseweg 64,
Leiden, 2333 AL, The Netherlands
The FIN1 gene from the yeast Saccharomyces cerevisiae encodes a basic
protein with putative coiled-coil regions. We have identified this
protein as an binding partner of the yeast 14-3-3 proteins. In large-budded cells a green fluorescent protein (GFP)-Fin1 fusion protein is
visible as a filament between the two spindle pole bodies. In resting
cells the protein is undetectable and in small-budded cells it is
localized in the nucleus. During late mitosis it localizes on the
spindle pole bodies. Filaments of cyano fluorescent protein tagged Fin1
co-localize with filaments of GFP tagged Tub1 only in large budded
cells. By electron and atomic force microscopy we showed that purified
recombinant Fin1p self-assembles into filaments with a diameter of
approximately 10 nm. Our results indicate that the Fin1 protein forms a
novel cell cycle-specific filament additional to the microtubules
between the spindle pole bodies of dividing yeast cells.
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