Fig 4.
Myostatin prodomain blocks the interaction of mature myostatin with ECD_ACRIIB. SPR sensorgrams of the interactions of immobilized ECD_ACRIIB with 10 nm myostatin preincubated with 0, 1, 2, 5, 10, 20, 50 and 100 nm myostatin prodomain are shown. Various concentrations of myostatin prodomain and 10 nm myostatin were preincubated in 20 mm Hepes, 150 mm NaCl, 5 mm EDTA and 0.005% Tween-20 (pH 7.5) for 30 min at room temperature, and were injected over CM5 sensorchips containing immobilized ECD_ACRIIB. For the sake of clarity, the concentrations of myostatin prodomain injected over the sensorchip are not indicated in the panels; the SPR response decreased in parallel with the increase in myostatin prodomain concentration. The insert shows that the value of the apparent association rate kobs decreased with the increase in myostatin prodomain concentration. Note that 50 nm myostatin prodomain completely eliminated the interaction; half-maximal inhibition was achieved with ∼ 1 × 10−8 m myostatin prodomain. RU - SPR Response Units.