File S1 .xlsx

Sequence confirmation (LC-MS/MS) of six repeat region of spider dragline silk (MaSp1), expressed in tobacco by encoding in nucleus and plastids. 

The total soluble protein from MaSp1nuc and MaSp1pla were His-trap purified using methods previously described 18, and resolved on SDS-PAGE gels (4-20% Mini-PROTEAN TGX, BioRad). Bands corresponding to 25 kDa and 50 kDa for MaSp1pla and 25 kDa for MaSp1nuc were excised, destained and digested with TPCK-treated trypsin (Worthington Biochemical Corporation). The resulting peptides were separated on a reversed-phase nanospray column (NTCC-360/75-3-105, NIKKYO technos) and then applied to a Q Exactive Hybrid Quadrupole-Orbitrap mass spectrometer (Thermo Fisher Scientific). MS and MS/MS data were obtained using the TOP10 method. The acquired data were processed using Proteome Discoverer 2.4 (Thermo Fisher Scientific) with integrated Mascot (version 2.7, Matrix Science). The MSMS data were searched against the NCBIprot database (Taxonomy: Other green plants) and the in-house database including the MaSp1 protein using the following parameters: enzyme = trypsin; maximum missed cleavages = 3; variable modifications = Acetyl (Protein N-term), Gln- > pyro-Glu (N-term Q), Oxidation (M), Propionamide (C); product mass tolerance = ± 15 ppm; product mass tolerance = ± 30 milli mass unit; instrument type = ESI-TRAP.