The SWIB/MDM2 protein domain, short for SWI/SNF complex B/MDM2, has been found in both SWI/SNF complex B (SWIB) and the negative regulator of the p53 tumor suppressor MDM2, which are homologous and share a common fold. The SWIB domain is a conserved region found within proteins in the SWI/SNF (SWItch/Sucrose Non-Fermentable) family of complexes. SWI/SNF complex proteins display helicase and ATPase activities and are thought to regulate transcription of certain genes by altering the chromatin structure around those genes. The mammalian complexes are made up of 9-12 proteins called BAFs (BRG1-associated factors). MDM2 is an inhibitor of p53 tumor repressor. It binds to the transactivation domain and down-regulates the ability of p53 to activate transcription. This family corresponds to the SWIB domain and the p53 binding domain of MDM2.
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