Myostatin (MSTN) also known as growth differentiation factor 8 (GDF-8) a myokine, a protein produced and released by my°Cytes. It inhibit myogenesis including muscle cell growth and differentiation. Myostatin is a secreted growth differentiation factor that is a member of the TGF beta protein family. Besides, Follistatin Like Protein 3 (FSTL3) has been identified as an interactor of MSTN, thus a binding ELISA assay was conducted to detect the interaction of recombinant rat MSTN and recombinant rat FSTL3. Briefly, MSTN were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100uL were then transferred to FSTL3-coated microtiter wells and incubated for 2h at 37°C. Wells were washed with PBST and incubated for 1h with anti-MSTN pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37°C. Finally, add 50µL stop solution to the wells and read at 450nm immediately. The binding activity of MSTN and FSTL3 was shown in Figure 1, and this effect was in a dose dependent manner.