Marie K Cross, Maureen A Powers
Department of Cell Biology, Emory University, GA 30322, US.
Nup98 is a 98 kDa protein of the nuclear pore complex (NPC), the large macromolecular structure responsible for trafficking between the nucleus and the cytoplasm. NPC proteins are collectively referred to as nucleoporins, and are typically, but not always, named as Nup followed by the respective molecular weight in kDa. A subset of nucleoporins contains a repeat domain with multiple interspersed copies of a phenylalanine-glycine (FG) core motif. Nup98 is the only metazoan nucleoporin with the glycine-leucine-phenylalanine-glycine (GLFG) variant of these repeats. Here we provide a detailed summary of Nup98 and its many reported functions. The NUP98 gene encodes multiple transcripts that vary as a result of differential splicing. Nup98 is expressed in two major forms: the Nup98 protein derived from a 3 kb messenger RNA (mRNA), or the Nup98-Nup96 polyprotein translated from an 8 kb message. Both forms undergo autocatalyzed proteolysis to release the mature, 90 kDa Nup98 from the amino (N) terminus, and either an 8 kDa peptide or the Nup96 protein from the carboxy (C) terminus. Nup96 is a component of a major structural subcomplex of the NPC. Nup98 is a dynamic nucleoporin that moves on and off the NPC and shuttles between nuclear and cytoplasmic compartments. Nup98 is a key player in RNA export from the nucleus, has a role in the import of some nuclear proteins, and contributes to proper mitotic regulation during cell division. Nup98 is targeted by several viruses to selectively enhance viral expression and, in turn, NUP98 transcription is upregulated by the interferon γ-mediated immune response of the cell. The NUP98 gene is a site of chromosomal translocations that lead to expression of chimeric proteins containing the GLFG repeat domain of Nup98 fused to a variety of partner proteins. These fusions are associated most often with the development of acute myelogenous leukemia. Thus, Nup98 is a remarkably diverse and multi-talented nucleoporin with additional functions that are still being explored.
Alternative names for this molecule: 98 kDa nucleoporin; ADAR2; ADIR2; GLFG-repeat containing nucleoporin; Nuclear pore complex protein Nup98; Nuclear pore complex protein Nup98-Nup96; Nucleoporin 98; Nucleoporin 98kD; Nucleoporin 98kDa; Nucleoporin Nup98; NUP196; NUP96; Nup96; NUP98; Nup98; Nup98-Nup96; p97