The spindle pole body component Spc98p interacts with the gamma-tubulin-like Tub4p of Saccharomyces cerevisiae at the sites of microtubule attachment

EMBO J. 1996 Aug 1;15(15):3899-911.


Tub4p is a novel tubulin found in Saccharomyces cerevisiae. It most resembles gamma-tubulin and, like it, is localized to the yeast microtubule organizing centre, the spindle pole body (SPB). In this paper we report the identification of SPC98 as a dosage-dependent suppressor of the conditional lethal tub4-1 allele. SPC98 encodes an SPB component of 98 kDa which is identical to the previously described 90 kDa SPB protein. Strong overexpression of SPC98 is toxic, causing cells to arrest with a large bud, defective microtubule structures, undivided nucleus and replicated DNA. The toxicity of SPC98 overexpression was relieved by co-overexpression of TUB4. Further evidence for an interaction between Tub4p and Spc98p came from the synthetic toxicity of tub4-1 and spc98-1 alleles, the dosage-dependent suppression of spc98-4 by TUB4, the binding of Tub4p to Spc98p in the two-hybrid system and the co-immunoprecipitation of Tub4p and Spc98p. In addition, Spc98-1p is defective in its interaction with Tub4p in the two-hybrid system. We suggest a model in which Tub4p and Spc98p form a complex involved in microtubule organization by the SPB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Cycle
  • Cell Survival
  • Cloning, Molecular
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Fungal
  • Genes, Suppressor
  • Microscopy, Fluorescence
  • Molecular Sequence Data
  • Phenotype
  • Plasmids / metabolism
  • Promoter Regions, Genetic
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae / ultrastructure
  • Saccharomyces cerevisiae Proteins*
  • Spindle Apparatus / metabolism*
  • Temperature
  • Tubulin / metabolism*


  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • TUB4 protein, S cerevisiae
  • Tubulin