Proteomics-based identification of proteins interacting with Smad3: SREBP-2 forms a complex with Smad3 and inhibits its transcriptional activity.

Smad3 is an important component of transforming growth factor-beta (TGFbeta) intracellular signalling. To identify novel interacting proteins of Smad3, we performed pull-down assays with Smad3 constructs fused to glutathione-S-transferase. Proteins which formed complexes with these constructs were analyzed by two-dimensional gel electrophoresis, and were identified by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry.