Brl1p – A Novel Nuclear Envelope Protein Required for Nuclear Transport

Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Traffic (Impact Factor: 4.35). 07/2005; 6(6):502-17. DOI: 10.1111/j.1600-0854.2005.00295.x
Source: PubMed


In this article, we identify a cold-sensitive mutant of Xpo1p designated as xop1-2 (but will be referred to from here on as xpo1-ok) that is synthetically lethal with srm1-1, a Saccharomyces cerevisiae RCC1 homolog. xpo1-ok was a novel mutated allele with a single point mutation, T283P. Suppressors of xpo1-ok were isolated, and one of them was found to encode a novel nuclear envelope integral membrane protein designated as Brl1p (Brr6 like protein no. 1). Brl1p is homologous with Brr6p at the C-terminal domain, which is well conserved in the Brr6/Brl1 family. To characterize the function of Brl1p, a series of temperature-sensitive mutants of Brl1p were isolated. All of brl1 mutations were localized to the conserved C-terminal domain that is essential for a function of Brl1p. Some brl1 alleles showed defects in nuclear export of either mRNA or protein, and nuclear pore clustering, similar to brr6-1. The cellular localization of Brl1p is also similar to that of Brr6p. The genetic analysis suggested that Brl1p functionally interacts with Brr6p. An interaction of Brl1p with Brr6p was shown by the two-hybrid method. We hypothesize that Brl1p functions for nuclear export as a complex with Brr6p.

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Available from: Takeharu Nishimoto, Oct 14, 2014
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    • "BRR6 and BRL1 (BRR6 related 1) are essential components of the nuclear periphery that are required for efficient nuclear transport (de Bruyn Kops and Guthrie, 2001; Saitoh et al., 2005). Loss of either can be complemented by S. pombe or Pneumocystis carinii brr6 + (Saitoh et al., 2005; Lo Presti et al., 2007). BRL1 and BRR6 are thought to have arisen from a genome duplication event that is specific to the Saccharomycotina subphylum of the Ascomycota. "
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    • "BRR6 was able to suppress the growth defect of brl1 mutants, which were synthetically lethal with brr6-1. Brl1 and Brr6 interacted with each other in a two-hybrid analysis (Saitoh et al., 2005). However, we found that BRL1 could not suppress apq12⌬ (unpublished results). "
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