Homeodomain of yeast repressor alpha 2 contains a nuclear localization signal

Proc Natl Acad Sci U S A. 1990 Sep;87(18):6954-8. doi: 10.1073/pnas.87.18.6954.


The yeast repressor alpha 2 is shown, by analysis of deletion-bearing alpha 2-beta-galactosidase hybrid proteins, to have two structurally distinct nuclear localization signals. The cellular location of hybrid proteins was determined by indirect immunofluorescence and optical sectioning of whole fixed yeast cells. The two nuclear localization signals are far apart in the alpha 2 primary structure and do not have any sequence homology. One signal is, as reported previously, within the aminoterminal 13 amino acids of alpha 2. Deletion of only this aminoterminal signal has no evident effect on nuclear localization. The second signal is in a central portion of alpha 2, within the alpha 2 homeodomain. Since this signal is within the amino terminus of the alpha 2 homeodomain, the homeodomain mediates nuclear localization in addition to, and independently of, DNA binding. Deletion of only this second signal results in inefficient localization and accumulation of mutant protein at discrete sites on the nuclear envelope assumed to be nuclear pores. We propose that the two signals in alpha 2 are functionally distinct and act at different steps in a localization pathway.

Publication types

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

MeSH terms

  • Base Sequence
  • Cell Nucleus / metabolism
  • Chromosome Deletion
  • DNA-Binding Proteins / genetics*
  • Fungal Proteins / genetics*
  • Genes, Fungal*
  • Genes, Homeobox*
  • Homeodomain Proteins*
  • Molecular Sequence Data
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Oligonucleotide Probes
  • Protein Sorting Signals / genetics
  • Repressor Proteins*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins


  • DNA-Binding Proteins
  • Fungal Proteins
  • Homeodomain Proteins
  • MATA2 protein, S cerevisiae
  • Nuclear Proteins
  • Oligonucleotide Probes
  • Protein Sorting Signals
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins