Figure 4. Atn directly binds STAT3.
(A) Computational approaches to examine the binding of Atn and pSTAT3 in silico. Atn is shown as a yellow stick model, the SH2 domain of STAT3-Y705-DNA complex is shown in purple ribbon. (B) Details of the binding site of Atn in the STAT3 SH2 domain. The protein backbone is portrayed as a transparent sky blue ribbon; the main residues involved in drug interactions are shown as labeled purple sticks. Atn is portrayed as atom-yellowed sticks-and-balls. (C) Chemical structure of Bio-Atn and Atn. (D) MDA-MB-231 cells were treated with 10 μM Biotin or Bio-Atn for 12 h, lysed, and the cell lysates were subjected to immunoprecipitation using S. agarose and Western blot using indicated antibodies. (E) MDA-MB-231 cells were treated with Bio-Atn (5 μM) in the presence or absence of Atn (25 μM) for 3 h, lysed, and the cell lysates were subjected to immunoprecipitation and Western blot. (F) 293T cells were transfected with wild type (WT) or mutant STAT3 (R688A, P689A, H694A, or P695A) for 24 h, lysed, the lysates were subjected to immunoprecipitation using S. agarose and Western blot using indicated antibodies.