Two microtubule-associated proteins required for anaphase spindle movement in Saccharomyces cerevisiae.
In many eucaryotic cells, the midzone of the mitotic spindle forms a distinct structure containing a specific set of proteins. We have isolated ASE1, a gene encoding a component of the Saccharomyces cerevisiae spindle midzone. Strains lacking both ASE1 and BIK1, which encodes an S. cerevisiae microtubule-associated protein, are inviable. The analysis of the phenotype of a bik1 ase1 conditional double mutant suggests that BIK1 and ASE1 are not required for the assembly of a bipolar spindle, but are essential for anaphase spindle elongation. The steady-state levels of Ase1p are regulated in a manner that is consistent with a function during anaphase: they are low in G1, accumulate to maximal levels after S phase and then drop as cells exit mitosis. Components of the spindle midzone may therefore be required in vivo for anaphase spindle movement. Additionally, anaphase spindle movement may depend on a dedicated set of genes whose expression is induced at G2/M.
Pellman
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Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
Bagget
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Tu
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Fink
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Tu
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D000705:Anaphase; D001483:Base Sequence; D002455:Cell Division; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D008854:Microscopy, Electron; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure
D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins