title: The rare TXNRD1_v3 ("v3") splice variant of human thioredoxin reductase 1 protein is targeted to membrane rafts by N-acylation and induces filopodia independently of its redox active site integrity.
abstract: The human selenoprotein thioredoxin reductase 1 (TrxR1), encoded by the TXNRD1 gene, is a key player in redox regulation. Alternative splicing generates several TrxR1 variants, one of which is v3 that carries an atypical N-terminal glutaredoxin domain. When overexpressed, v3 associates with membranes and triggers formation of filopodia. Here we found that membrane targeting of v3 is mediated by myristoylation and palmitoylation of its N-terminal MGC motif, through which v3 specifically targets membrane rafts. This was suggested by its localization in cholera toxin subunit B-stained membrane areas and also shown using lipid fractionation experiments. Utilizing site-directed mutant variants, we also found that v3-mediated generation of filopodia is independent of the Cys residues in its redox active site, but dependent upon its membrane raft targeting. These results identify v3 as an intricately regulated protein that expands TXNRD1-derived protein functions to the membrane raft compartment.
authors: Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors: Marcus
authors: M
authors: Cebula
authors: Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School, 2193 Johannesburg, South Africa.
authors: Naazneen
authors: N
authors: Moolla
authors: Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School, 2193 Johannesburg, South Africa.
authors: Alexio
authors: A
authors: Capovilla
authors: Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden. Electronic address: Elias.Arner@ki.se.
authors: Elias S J
authors: ESJ
authors: Arnér
mesh_terms: D000215:Acylation; D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D020134:Catalytic Domain; D045744:Cell Line, Tumor; D003545:Cysteine / Q000235:genetics; D054477:Glutaredoxins / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008055:Lipids / Q000737:chemistry; D021962:Membrane Microdomains / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010084:Oxidation-Reduction; D017434:Protein Structure, Tertiary; D011554:Pseudopodia / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D054481:Thioredoxin Reductase 1 / Q000737:chemistry* / Q000235:genetics*
chemical_list: D054477:Glutaredoxins; D008055:Lipids; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C516124:TXNRD1 protein, human; D054481:Thioredoxin Reductase 1; D003545:Cysteine