A novel complex of membrane proteins required for formation of a spherical nucleus.
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.
Siniossoglou
S
S
BZH, Biochemie-Zentrum Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany.
Santos-Rosa
H
H
Rappsilber
J
J
Mann
M
M
Hurt
E
E
D000595:Amino Acid Sequence; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal
D005656:Fungal Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C116365:SPO7 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins