Genetic and physical interactions between Srp1p and nuclear pore complex proteins Nup1p and Nup2p.
Nup1p is a yeast nuclear pore complex protein (nucleoporin) required for nuclear protein import, mRNA export and maintenance of normal nuclear architecture. We have used a genetic approach to identify other proteins that interact functionally with Nup1p. Here we describe the isolation of seventeen mutants that confer a requirement for Nup1p in a background in which this protein is normally not essential. Some of the mutants require wild-type Nup1p, while others are viable in combination with specific nup1 alleles. Several of the mutants show nonallelic noncomplementation, suggesting that the products may be part of a hetero-oligomeric complex. One is allelic to srp1 which, although it was identified in an unrelated screen, was shown to encode a protein that is localized to the nuclear envelope (Yano, R., M. Oakes, M. Yamaghishi, J. A. Dodd, and M. Nomura. 1992. Mol. Cell. Biol. 12:5640-5651). We have used immunoprecipitation and fusion protein precipitation to show that Srp1p forms distinct complexes with both Nup1p and the related nucleoporin Nup2p, indicating that Srp1p is a component of the nuclear pore complex. The distant sequence similarity between Srp1p and the beta-catenin/desmoplakin family, coupled with the altered structure of the nuclear envelope in nup1 mutants, suggests that Srp1p may function in attachment of the nuclear pore complex to an underlying nuclear skeleton.
Belanger
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Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710.
Kenna
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Wei
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Davis
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D000483:Alleles; D001483:Base Sequence; D003001:Cloning, Molecular; D005804:Genes, Lethal; D005816:Genetic Complementation Test; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009685:Nuclear Envelope / Q000378:metabolism*; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins / Q000378:metabolism*; D018272:Porins / Q000378:metabolism*; D011233:Precipitin Tests; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D028901:alpha Karyopherins
D008565:Membrane Proteins; C064550:NUP1 protein, S cerevisiae; C400753:NUP2 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D018272:Porins; D029701:Saccharomyces cerevisiae Proteins; D028901:alpha Karyopherins