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The EMBO Journal
(1998) 17, 6449–6464, doi:10.1093/emboj/17.22.6449
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| A novel complex of membrane proteins required for formation of a spherical nucleus |
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Symeon Siniossoglou1, 4, Helena Santos-Rosa1, 4, Juri Rappsilber2, Mathias Mann3 and Ed Hurt1
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1 BZH, Biochemie-Zentrum Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
2 EMBL, Meyerhofstrasse1, D-69117 Heidelberg, Germany
3 Center for Experimental Bioinformatics, Odense University, Odense, Denmark
4 S.Siniossoglou and H.Santos-Rosa contributed equally to this work
To whom correspondence should be addressed
Ed Hurt, cg5@ix.urz.uni-heidelberg.de
Received 14 August 1998; Revised 23 September 1998; Accepted 24 September 1998.
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| Abstract |
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| Two membrane proteins were identified through their genetic interaction with the nucleoporin Nup84p and shown to participate in nuclear envelope morphogenesis in yeast. One component is a known sporulation factor Spo7p, and the other, Nem1p, a novel protein whose C-terminal domain is conserved during eukaryotic evolution. Spo7p and Nem1p localize to the nuclear/ER membrane and behave biochemically as integral membrane proteins. Nem1p binds to Spo7p via its conserved C-terminal domain. Although cells without Spo7p or Nem1p are viable, they exhibit a drastically altered nuclear morphology with long, pore-containing double nuclear membrane extensions. These protrusions emanate from a core nucleus which contains the DNA, and penetrate deeply into the cytoplasm. Interestingly, not only Spo7- and Nem1-, but also several nucleoporin mutants are defective in sporulation. Thus, Spo7p and Nem1p, which exhibit a strong genetic link to nucleoporins of the Nup84p complex, fulfil an essential role in formation of a spherical nucleus and meiotic division. |
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| Keywords: membrane biogenesis, nuclear envelope, nuclear morphology, nuclear pore complex, sporulation |
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