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. Author manuscript; available in PMC: 2009 Jun 1.
Published in final edited form as: Mol Cancer Ther. 2008 Jun;7(6):1639–1646. doi: 10.1158/1535-7163.MCT-07-2373

Figure 1. Gambogic acid inhibits binding of FITC-BH3 peptide to anti-apoptotic Bcl-2 family proteins.

Figure 1

A, Structure of gambogic acid. B–D, For peptide competition experiments in FPA mode, 100 nM of Bcl-2 family proteins, including Bcl-XL, Bcl-2, Bcl-W, Bcl-B, Bfl-1 or Mcl-1, were incubated with various concentrations of gambogic acid (GA) for 2 min in PBS buffer, then 5 nM FITC-conjugated-Bid BH3 peptide was added. E, GA does not interfere with FITC-Bid BH3 peptide alone, tested as a control. Fluorescence polarization (milli-Polars [mP]) was measured after 10 min. Interaction of gambogic acid with FITC-conjugated Bid BH3 peptide alone was used as a control. Note that background FP for these assays from FITC-BH3 peptide in the absence of Bcl-2 family protein is ~50–70 mP (FP min), while the maximum FP ranges from ~130 to ~190 mP (FP max), depending on the Bcl-2-family member.