Fig. 3.

Kinetics measurements with α_Vβ₆ fragments and pro-TGF-β1. (A–F) SPR sensorgrams (thin black lines) are shown with fits (thick gray lines). α_Vβ₆ fragments and metal ions are indicated. Concentrations used for unclasped integrin α_Vβ₆ ectodomain and α_Vβ₆ headpiece were 100, 50, 20, 10, 5, and 0 nM in both 1 mM Mg²⁺/1 mM Ca²⁺ and 1 mM Mn²⁺/0.2 mM Ca²⁺. Concentrations used for integrin α_Vβ₆ head were 50, 20, 10, 5, 2, and 0 nM in 1 mM Mg²⁺/1 mM Ca²⁺ and 500, 200, 100, 50, 20, 10, and 0 nM in 1 mM Mn²⁺/0.2 mM Ca²⁺. (G) K_D and kinetic rates. Values are mean ± difference from mean of two independent experiments. Clasped ectodomain data from ref. 11 are shown for comparison. N.M. not measureable, off-rate is too low.