Found in a complex with
SMAD1 and
YY1 (By similarity). Interacts with
CITED2 (By similarity). Monomer; in the absence of TGF-beta activation. Heterodimer; on TGF-beta activation. Composed of two molecules of a C-terminally phosphorylated R-SMAD molecule,
SMAD2 or
SMAD3, and one molecule of
SMAD4 to form the transcriptional active
SMAD2/
SMAD3-
SMAD4 complex. Found in a ternary complex composed of
SMAD4,
STK11/LKB1 and
STK11IP. Interacts with
ATF2,
COPS5,
DACH1, MSG1,
SKI,
STK11/LKB1,
STK11IP and
TRIM33. Interacts with
ZNF423; the interaction takes place in response to
BMP2 leading to activation of transcription of BMP target genes. Interacts with
ZNF521; the interaction takes place in response to
BMP2 leading to activation of transcription of BMP target genes. Interacts with
USP9X. Interacts (via the MH1 and MH2 domains) with
RBPMS. Interacts with
WWTR1 (via coiled-coil domain). Component of the multimeric complex
SMAD3/
SMAD4/
JUN/
FOS which forms at the AP1 promoter site; required for synergistic transcriptional activity in response to TGF-beta. Interacts with
CITED1. Interacts with
PDPK1 (via PH domain) (By similarity). Interacts with
VPS39; this interaction affects heterodimer formation with
SMAD3, but not with
SMAD2, and leads to inhibition of
SMAD3-dependent transcription activation. Interactions with
VPS39 and
SMAD2 may be mutually exclusive. Interacts with
ZC3H3 (By similarity). Interacts (via MH2 domain) with
ZNF451 (via N-terminal zinc-finger domains) (PubMed:24324267). Identified in a complex that contains at least
ZNF451,
SMAD2,
SMAD3 and
SMAD4 (PubMed:24324267). Interacts weakly with
ZNF8 (PubMed:12370310). Interacts with
NUP93 and
IPO7; translocates
SMAD4 to the nucleus through the NPC upon
BMP7 stimulation resulting in activation of
SMAD4 signaling (PubMed:26878725). Interacts with
CREB3L1, the interaction takes place upon
TGFB1 induction and
SMAD4 acts as
CREB3L1 coactivator to induce the expression of genes involved in the assembly of collagen extracellular matrix (PubMed:25310401). Interacts with
DLX1 (PubMed:14671321). Interacts with
ZBTB7A; the interaction is direct and stimulated by
TGFB1 (PubMed:25514493). Interacts with
CREBBP; the recruitment of this transcriptional coactivator is negatively regulated by
ZBTB7A (PubMed:25514493). Interacts with
EP300; the interaction with this transcriptional coactivator is negatively regulated by
ZBTB7A (PubMed:25514493). Interacts with
HDAC1 (PubMed:25514493).
UniProt