Nuclear import of Spo12p, a protein essential for meiosis.
In Saccharomyces cerevisiae, Spo12p is involved in mitosis and is essential for meiosis. We found that Spo12p is imported into the nucleus by the karyopherin Kap121p. A complex containing Spo12p and Kap121p was isolated from cytosol and was also reconstituted with recombinant proteins, indicating that this interaction is direct. Spo12p was mislocalized to the cytosol in pse1-1, a temperature-sensitive strain harboring a mutation of Kap121p, at the permissive temperature, confirming an essential role for Kap121p in Spo12p import. Spo12p was also mislocalized in a pse1-1/pse1-1 homozygous strain, suggesting it is imported via the same pathway in diploid cells. Furthermore, we found that pse1-1/pse1-1 shows a sporulation defect similar to that of spo12Delta/spo12Delta. In addition, we have characterized the Spo12p nuclear localization signal, mapped it to residues 76-130, and identified residues within this region that are important for nuclear localization signal function.
Laboratory of Cell Biology, Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021, USA.
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D000595:Amino Acid Sequence; D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D008540:Meiosis; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D009687:Nuclear Proteins; C416648:SPO12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins