High impact information on NUP116

• A stretch of 140 amino acids within Nup145p is conserved in two other yeast nucleoporins, Nup116p and Nup100p, and in an uncharacterized C. elegans protein [1].
• Cex1p binds tRNA saturably, and associates with the nuclear pore complex by interacting directly with Nup116p [2].
• Gle2p is anchored at the nuclear envelope (NE) via a short Gle2p-binding motif within Nup116p called GLEBS [3].
• A nuclear export signal in Kap95p is required for both recycling the import factor and interaction with the nucleoporin GLFG repeat regions of Nup116p and Nup100p [4].
• In vivo interaction was demonstrated by isolation of Kap95p from yeast nuclear lysates in either protein A-tagged Nup116p or protein A-tagged Nup100p complexes [4].

Biological context of NUP116

• First, deletion mutagenesis analysis of NUP116 revealed that the GLFG region was required for NPC function [5].
• The GLFG repetitive region of the nucleoporin Nup116p interacts with Kap95p, an essential yeast nuclear import factor [5].
• Moreover, deletion of either half of Nup116p's GLFG repeats or replacement of Nup116p's GLFG region with either Nup100p's GLFG region or Nsp1p's FXFG repetitive region abolishes the function of Nup116p [5].
• We have also analyzed the synthetic lethal phenotypes among GLFG nucleoporin mutant alleles, and found that strains harboring nup116 and either nup100 or nup145 mutations were not viable [6].
• Interestingly, NUP100 and NUP116 are both flanked by a histidine tRNA gene and a transposon element suggesting that they may have arisen by gene duplication [7].

Anatomical context of NUP116

• Nup116p is a member of a family of five yeast nuclear pore complex (NPC) proteins that share an amino terminal region of repetitive tetrapeptide "GLFG" motifs [5].
• Previous experiments characterized the unique morphological perturbations that occur in a nup116 null mutant: temperature-sensitive formation of nuclear envelope seals over the cytoplasmic face of the NPC (Wente, S. R., and G. Blobel. 1993. J. Cell Biol. 123:275-284) [5].
• In situ hybridization with poly(dT) probes showed the accumulation of polyadenylated RNA in the nuclei of arrested nup116 delta cells, sometimes in the form of punctate patches at the nuclear periphery [8].
• Immuno-gold labeling suggested that Nup159p may be attached to the cytoplasmic ring, whereas Nup116p may be associated, partly, with the cytoplasmic filaments [9].

Physical interactions of NUP116

• Thus, the in vivo function of Gle2p is strictly coupled to the short GLEBS within Nup116p which links this putative mRNA transport factor to the nuclear pores [10].
• Nup100p and Nup116p can be co-immunoprecipitated from whole-cell extracts with Upf1p, confirming in vitro the interaction identified by the two-hybrid analysis [11].
• Assembly and preferential localization of Nup116p on the cytoplasmic face of the nuclear pore complex by interaction with Nup82p [12].
• We have additionally shown that a peptide from the N terminus of the nucleoporin Nup145p-C binds Nup116p-C [13].

Regulatory relationships of NUP116

• In live yeast, mutated Snl1p could not substitute for wild-type Snl1p in suppressing the lethal defect caused by truncation of the Nup116p nuclear pore component [14].

Other interactions of NUP116

• The amino-terminal half of Nup145p is similar to two previously identified GLFG nucleoporins, Nup116p and Nup100p (Wente, S. R., M. P. Rout, and G. Blobel. 1992. J. Cell Biol. 119:705-723) [6].
• Gle2p physically associated with Nup116p in vitro, and the interaction required the N-terminal region of Nup116p [15].
• Decreased levels of NPC-associated Nsp1p and Nup116p were observed [16].
• Finally, synthetic lethal interactions were found between mutant alleles of NUP116 and all members of the Nup82p complex [17].
• Three individual members of this family, NUP49, NUP100, and NUP116, have been isolated and then characterized by a combination of molecular genetics and immunolocalization [7].

Analytical, diagnostic and therapeutic context of NUP116

• Peptide sequence analysis reveals that p97 contains a GLFG motif which defines a family of yeast nuclear pore proteins, as well as a peptide that is identical at 11/15 amino acids to a specific member of the GLFG family, NUP116 [18].
• Immunoprecipitation experiments using yeast cell lysates resulted in the coisolation of a Nup116p-Nup82p subcomplex [12].
• Moreover, NPC localization of Nup116p was specifically diminished in a nup82-Delta108 mutant after growth at 37 degrees C. Immunoelectron microscopy analysis showed Nup116p was localized on both the cytoplasmic and nuclear NPC faces [12].
• Binding of Nup85p to the GLFG region of Nup116p was quantified in vitro (K(D) = 1.5 micro M) and was confirmed in vivo using the yeast two-hybrid assay [19].

References