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. 2016 Feb 2;14(8):1695–1704. doi: 10.1111/pbi.12530

Figure 6.

Figure 6

Furin enhances the accumulation of biologically active TGF‐β1. (a) Native and codon‐optimized cSP‐LAP‐TGF‐β1 were transiently expressed in Nicotiana benthamiana leaves with or without co‐expression of furin. The percentage of secreted cSP‐LAP‐TGF‐β1 was determined at 5 dpi by determining the amount of cytokine in apoplast fluids versus crude extracts (n = 5, error bars indicate standard error). (cSP: Arabidopsis thaliana chitinase signal peptide; TSP: total soluble protein). Asterisk indicates significant differences as determined by a Welch's t‐test (*P < 0.05). (b) Mature TGF‐β1‐specific Western blot analysis with a polyclonal antibody at 5 dpi under reducing conditions of apoplast fluids and crude extracts containing native or codon‐optimized cSP‐LAP‐TGF‐β1 with or without co‐expression of furin (EV: empty vector control; pc: codon‐optimized; +: furin co‐expression). (c) Biological activity of 5 ng/mL recombinant TGF‐β1 (rTGF‐β1) and plant‐produced TGF‐β1 (from dpi 5) as determined by the induction of luciferase expression in MLEC cells. Relative activity of plant‐produced TGF‐β1 versus recombinant TGF‐β1 (in %) is given (n = 3, error bars indicate standard error).