Figure 2.

TSRI265 binds directly to integrin α_vβ₃, suppressing the interaction between MMP2 and integrin α_vβ₃. (A) TSRI265 specifically blocks integrin α_vβ₃ binding to MMP2 without affecting interaction of α_vβ₃ with its classical ligand, vitronectin. Solid phase receptor binding of biotinylated MMP2 (bMMP2) or bVN to integrin α_vβ₃ was performed in the presence or absence of 3 μM TSRI265/TSRI359 or 100 μM cyclic RGD or RAD peptide. Binding was determined colorimetrically with an HRP-conjugated antibiotin mAb as described in the Materials and Methods. (B–D) TSRI265 binds specifically and saturably to integrin α_vβ₃ in an RGD-independent manner. Purified integrins α_vβ₃ and α₅β₁ were coated onto microtiter wells, which were subsequently blocked and incubated with ¹⁴C-labeled TSRI265 alone (B) or in the presence or absence of a 25-fold molar excess of unlabeled TSRI265 or TSRI359 (C) or 100 μM cyclic RGD or RAD peptide (D). bVN was used as a control and detected colorimetrically with an HRP-conjugated antibiotin mAb as described in Materials and Methods.