Figure 3.

Sensitivity and specificity of irisin antibodies. A-C: Detection of different amounts of recombinant irisin with antibodies A, B, and C. A: Irisin amounts per lanes 1–8: 20, 4, 2, 1, 0.5, 0.25, 0.125, and 0.062 ng. The first lane, containing 20 ng recombinant irisin, was excluded to calculate the linearity (when included: R² = 0.9781). B: Irisin amounts per lane 1–7: 4, 2, 1, 0.5, 0.25, 0.125, and 0.062 ng. C: Irisin amounts per lane 1–8: 4, 2, 1, 0.5, 0.25, 0.125, 0.062, and 0.031 ng. Linearity of detection is shown for each antibody in the lower panel (details in Supplementary Figs. S2A–C). D: Detection of non-glycosylated and glycosylated recombinant irisin, and FNDC5/irisin in human*, mouse and bovine serum/plasma, and muscle with antibody C (upper panel). The antibody was pre-incubated with recombinant irisin in a parallel blot (lower panel). ^∗Human serum sample: HS 1 (acute exercise; details in Supplementary Table S1). M: molecular weight marker. Regions of interest are marked by boxes.