The unconventional myosin, Myo2p, is a calmodulin target at sites of cell growth in Saccharomyces cerevisiae

J Cell Biol. 1994 Feb;124(3):315-23. doi: 10.1083/jcb.124.3.315.

Abstract

Myo2p is an unconventional myosin required for polarized growth in Saccharomyces cerevisiae. Four lines of evidence suggest that (a) Myo2p is a target of calmodulin at sites of cell growth, and (b) the interaction between Myo2p and calmodulin is Ca2+ independent. First, as assessed by indirect immunofluorescence, the distributions of Myo2p and calmodulin are nearly indistinguishable throughout the cell cycle. Second, a genetic analysis indicates that mutations in CMD1 show allele-specific synthetic lethality with the myo2-66 conditional mutation. Mutations that inactivate the Ca(2+)-binding sites of calmodulin have little or no effect on strains carrying myo2-66, whereas an allele with a mutation outside the Ca(2+)-binding sites dramatically increases the severity of the phenotype conferred by myo2-66. Third, Myo2p coimmunoprecipitates with calmodulin in the presence of Ca2+ or EGTA. Finally, we used a modified gel overlay assay to demonstrate direct interaction between calmodulin and fusion proteins containing portions of Myo2p. Calmodulin binds specifically to the region of Myo2p containing six tandem repeats of a motif called an IQ site. Binding occurs in either Ca2+ or EGTA, and only two sites are required to observe binding.

Publication types

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

MeSH terms

  • Alleles
  • Base Sequence
  • Calcium / metabolism
  • Calmodulin / genetics
  • Calmodulin / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Division
  • Cytoskeletal Proteins
  • Egtazic Acid / pharmacology
  • Fluorescent Antibody Technique
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Molecular Sequence Data
  • Mutation
  • Myosin Heavy Chains*
  • Myosin Type II*
  • Myosin Type V*
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Schizosaccharomyces pombe Proteins*

Substances

  • Calmodulin
  • Carrier Proteins
  • Cytoskeletal Proteins
  • Fungal Proteins
  • MYO2 protein, S cerevisiae
  • MYO2 protein, S pombe
  • Recombinant Fusion Proteins
  • SPA2 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Schizosaccharomyces pombe Proteins
  • Egtazic Acid
  • Myosin Type II
  • Myosin Type V
  • Myosin Heavy Chains
  • Calcium