Budd-Chiari syndrome in a patient heterozygous for the point mutation C20221T of the prothrombin gene.
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Adult↗
Biomedical subjects
B Kosova
Publications and source records attributed to B Kosova.
Mlp2p, a component of nuclear pore attached intranuclear filaments, associates with nic96p.
A fraction of the yeast nucleoporin Nic96p is localized at the terminal ring of the nuclear basket. When Nic96p was affinity purified from glutaraldehyde-treated spheroplasts, it was found to be associated with Mlp2p. Mlp2p, together with Mlp1p, are the yeast Tpr homologues, which form the nuclear pore-attached intranuclear filaments (Strambio-de-Castillia, C., Blobel, G., and Rout, M. P. (1999) J. Cell Biol. 144, 839-855). Double disruption mutants of MLP1 and MLP2 are viable and apparently not impaired in nucleocytoplasmic transport. However, overproduction of MLP1 causes nuclear accumulation of poly(A)(+) RNA in a chromatin-free area of the nucleus.
Amino Acid Sequence↗
Yeast nuclear pore complex assembly defects determined by nuclear envelope reconstruction.
Assembly of nuclear pore complexes (NPCs) is a critical yet poorly understood cellular function. One approach to studying NPC assembly is to identify yeast mutants defective in this process. This requires robust assays for NPC assembly that can be used for phenotypic analysis. We have previously reconstructed yeast nuclei from electron micrographs of serially sectioned cells to precisely determine the number of NPCs (Winey et al., 1997). Here we report the analysis of strains mutant in either of two nucleoporin-encoding genes, NIC96 (Zabel et al., 1996) and NUP192 (Kosova et al., 1999). Using conditional alleles of either gene, we have found that the NPC number falls significantly following shift to the restrictive temperature. We conclude that the drop in NPC number results from the failure to assemble new NPCs during cell divisions, leading to the dilution of NPCs that existed when the cells were shifted to the restrictive temperature. We are also able to document a subtle defect in NPC numbers in nup192-15 cells at their permissive temperature. The data presented here quantitatively demonstrate that NPC numbers fall in nic96-1 and nup192-15 strains upon shifting to the restrictive temperature, indicating that these gene products are required for NPC assembly.
Fungal Proteins↗
Nup192p is a conserved nucleoporin with a preferential location at the inner site of the nuclear membrane.
Human Nup93, the homologue of yeast Nic96p, is associated with a 205-kDa protein whose intracellular location and function is unknown. We show here that the yeast open reading frame YJL039c, which is homologous to this human p205, encodes the so far largest yeast nucleoporin. Accordingly, green fluorescent protein (GFP)-tagged YJL039c was localized to the nuclear pores and therefore named Nup192p. Affinity purification of ProtA-Nic96p from glutaraldehyde-fixed spheroplasts reveals association with Nup192p. NUP192 is essential for cell growth. A temperature-sensitive mutant nup192-15 is neither impaired in nuclear import of a SV40 nuclear localization sequence-containing reporter protein nor in mRNA export, but association of Nup49-GFP with nuclear pores is inhibited at the non-permissive temperature. By immunoelectron microscopy, Nup192p-ProtA is seen at the inner site of the nuclear pores, at a distance of 60 +/- 15 nm from the central plane of the pore. This suggests that Nup192p is an evolutionarily conserved structural component of the nuclear pore complex with a preferential location at the inner site of the nuclear membrane.
Amino Acid Sequence↗