Term Name:	SMAD protein complex
Synonyms:	SMAD complex, SMAD1 protein complex, SMAD2 protein complex, SMAD3 protein complex
Definition:	A protein complex that consists of only SMAD proteins; may be homomeric or heteromeric. Heteromeric complexes act as transcription factors while homomeric complexes exist but are transcriptionally inactive. Hetero- versus homotrimerization is largely enthalpy driven.
Ontology:	GO: Cellular Component [GO:0071141]    QuickGO    AmiGO