title: The membrane-topogenic vectorial behaviour of Nrf1 controls its post-translational modification and transactivation activity.
abstract: The integral membrane-bound Nrf1 transcription factor fulfils important functions in maintaining cellular homeostasis and organ integrity, but how it is controlled vectorially is unknown. Herein, creative use of Gal4-based reporter assays with protease protection assays (GRAPPA), and double fluorescence protease protection (dFPP), reveals that the membrane-topogenic vectorial behaviour of Nrf1 dictates its post-translational modification and transactivation activity. Nrf1 is integrated within endoplasmic reticulum (ER) membranes through its NHB1-associated TM1 in cooperation with other semihydrophobic amphipathic regions. The transactivation domains (TADs) of Nrf1, including its Asn/Ser/Thr-rich (NST) glycodomain, are transiently translocated into the ER lumen, where it is glycosylated in the presence of glucose to become a 120-kDa isoform. Thereafter, the NST-adjoining TADs are partially repartitioned out of membranes into the cyto/nucleoplasmic side, where Nrf1 is subject to deglycosylation and/or proteolysis to generate 95-kDa and 85-kDa isoforms. Therefore, the vectorial process of Nrf1 controls its target gene expression.
authors.affiliation: The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, University of Chongqing, Shapingba District, Chongqing, China. yiguozhang@cqu.edu.cn
authors.forename: Yiguo
authors.initials: Y
authors.lastname: Zhang
authors.forename: John D
authors.initials: JD
authors.lastname: Hayes
mesh_terms: D000818:Animals; D051379:Mice; D051266:Nuclear Respiratory Factor 1 / Q000235:genetics / Q000502:physiology*; D014176:Protein Biosynthesis; D015533:Transcriptional Activation
chemical_list: C495634:Nrf1 protein, mouse; D051266:Nuclear Respiratory Factor 1