Assays

Immunoprecipitation: Cells grown in 2-4x15 cm cell culture plates per sample were harvested by scraping on ice and stored at -80. Lysis was performed for 30 min at 4°C with MCLB buffer (50 mM Tris HCl pH 7.5, 150 mM NaCl, 0.5% NP40, 1x PhosStop,1x protease inhibitor) or Glycerol buffer (20 mM Tris pH 7.5, 150 mM NaCl, 10% glycerol, 5 mM EDTA, 0.5% TritonX, 1x PhosStop, inhibitor, 1x protease inhibitor). Samples were cleared from debris by centrifugation (20.000 g for 10 min at 4°C) and Ultrafree®-CL ...

LCL cells were cultured in lysine- and arginine-free DMEM (GIBCO) supplemented with 2 mM glutamine, 10% dialyzed FBS and antibiotics as well as with 146 mg/ml light (K0, Sigma) or heavy lysine (K8, Cambridge Isotope Laboratories) and 84 mg/ml light (R0, Sigma) or heavy (R10, CambridgeIsotope Laboratories) arginine, respectively. Cell pellets were lysed in 8 M Urea in 50 mM Tris-HCl pH 8.0. Protein concentrations were determined by a BCA assay and protein amounts were adjusted to equal concentrations. ...

Following HA-immunoprecipitation of C9orf72 from SMCR8 KO cells, proteins were precipitated with 20% TCA and incubated for 20 min on ice. After centrifugation at 20,000 x g, 4°C for 30 min, the supernatant was discarded, 10% cold TCA was added to pellets and centrifuged again. Pellets were washed 3x in cold acetone, centrifuged and then dried in a speed vacuum concentrator. For in-solution tryptic digestion, pellets were resolved in 50 mM ammonium bicarbonate (ABC) pH 8.0 with 10% acetonitrile ...

Proximity labeling: Cells were supplemented with 500 µM biotin-phenol (IrisBiotech) for 30 min at 37°C before addition of 1 mM H2O2 at room temperature. Cells were then first washed with quencher solution (1 mM sodium azide, 10 mM sodium ascorbate and 5 mM Trolox in DPBS), then with DPBS, scraped and harvested. Proteinase K digest: All steps were carried out at 4°C unless stated otherwise. Cells were washed and suspended in homogenization buffer I (10 mM KCl, 1.5 mM MgCl2, 10 mM HEPES-KOH and 1 ...

Cells were harvested and centrifuged 400g for 10 min at 4°C. Cell pellets were resuspended in STE-Buffer (250mM sucrose, 5mM Tris pH 7, 1mM EGTA, PI mix 1:500) and lysed with a 27-gauge needle. Samples were centrifuged 10 min at 800g to remove nuclei, then 10 min at 15.000g to remove mitochondria and finally 1 hour 100.000g. The resulting pellets were washed twice with 100mM Na2CO3 and centrifuged 30 min at 100000g after each wash. Pellets from membrane preparations were dissolved in lysis buffer ...

Nine patients per group were treated with either acitretin or vehicle control. Cerebrospinal fluid was collected before (baseline value) and after treatment. A volume of 5 µL of CSF per sample was subjected to proteolytic digestion in 50 mM ammonium bicarbonate with 0.1% sodium deoxycholate (Sigma Aldrich, Germany) as previously described (Pigoni et al., 2016). Briefly, protein disulfide bonds were reduced with dithiothreitol and sulfhydryl residues were alkylated using iodoacetamide. Proteins ...

2 x 108 wild-type or Tspan15-knockout HEK-293T cells were lysed in 1% digitonin lysis buffer containing protease inhibitor cocktail (Sigma-Aldrich). Lysates were pre-cleared with protein G sepharose prior to immunoprecipitation with Tspan15 mAb 1C12 chemically cross-linked to protein G sepharose with dimethyl pimelimidate (Thermo Fisher Scientific). Five independent immunoprecipitations were carried out for each cell type. Immunoprecipitation samples in non-reducing Laemmli buffer were subjected ...