Differential regulation of the Kar3p kinesin-related protein by two associated proteins, Cik1p and Vik1p

J Cell Biol. 1999 Mar 22;144(6):1219-33. doi: 10.1083/jcb.144.6.1219.

Abstract

The mechanisms by which kinesin-related proteins interact with other proteins to carry out specific cellular processes is poorly understood. The kinesin-related protein, Kar3p, has been implicated in many microtubule functions in yeast. Some of these functions require interaction with the Cik1 protein (Page, B.D., L.L. Satterwhite, M.D. Rose, and M. Snyder. 1994. J. Cell Biol. 124:507-519). We have identified a Saccharomyces cerevisiae gene, named VIK1, encoding a protein with sequence and structural similarity to Cik1p. The Vik1 protein is detected in vegetatively growing cells but not in mating pheromone-treated cells. Vik1p physically associates with Kar3p in a complex separate from that of the Kar3p-Cik1p complex. Vik1p localizes to the spindle-pole body region in a Kar3p-dependent manner. Reciprocally, concentration of Kar3p at the spindle poles during vegetative growth requires the presence of Vik1p, but not Cik1p. Phenotypic analysis suggests that Cik1p and Vik1p are involved in different Kar3p functions. Disruption of VIK1 causes increased resistance to the microtubule depolymerizing drug benomyl and partially suppresses growth defects of cik1Delta mutants. The vik1Delta and kar3Delta mutations, but not cik1Delta, partially suppresses the temperature-sensitive growth defect of strains lacking the function of two other yeast kinesin-related proteins, Cin8p and Kip1p. Our results indicate that Kar3p forms functionally distinct complexes with Cik1p and Vik1p to participate in different microtubule-mediated events within the same cell.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • DNA Primers / genetics
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Genes, Fungal
  • Kinesins / metabolism*
  • Mating Factor
  • Microtubule Proteins*
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Molecular Sequence Data
  • Mutation
  • Peptides / pharmacology
  • Phenotype
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid
  • Spindle Apparatus / metabolism

Substances

  • CIK1 protein, S cerevisiae
  • DNA Primers
  • Fungal Proteins
  • KAR3 protein, S cerevisiae
  • Microtubule Proteins
  • Microtubule-Associated Proteins
  • Peptides
  • Saccharomyces cerevisiae Proteins
  • VIK1 protein, S cerevisiae
  • Mating Factor
  • Kinesins