Transcriptional activator which is required for calcium-dependent dendritic growth and branching in cortical neurons. Recruits CREB-binding protein (CREBBP) to nuclear bodies. Component of the CREST-BRG1 complex, a multiprotein complex that regulates promoter activation by orchestrating a calcium-dependent release of a repressor complex and a recruitment of an activator complex. In resting neurons, transcription of the c-FOS promoter is inhibited by BRG1-dependent recruitment of a phospho-RB1-HDAC1 repressor complex. Upon calcium influx, RB1 is dephosphorylated by calcineurin, which leads to release of the repressor complex. At the same time, there is increased recruitment of CREBBP to the promoter by a CREST-dependent mechanism, which leads to transcriptional activation. The CREST-BRG1 complex also binds to the NR2B promoter, and activity-dependent induction of NR2B expression involves a release of HDAC1 and recruitment of CREBBP. Homodimer. Dimerization may be necessary for its function in neuronal dendritic development. Interacts (via C-terminus) with CREBBP (via N-terminus), EP300 and SMARCA4/BRG1. Interacts with the nBAF complex (By similarity). Association with CREBBP facilitates transcription while the association with SMARCA4/BRG1 suppresses CREST-mediated transcription in resting neurons. Localizes to nuclear bodies. Colocalizes with SGO1 at kinetochore (By similarity). Brain (at protein level). Also found in the heart, liver, kidney and testis. Detected as early as E18 in the developing cerebral cortex, and expression reaches its peak at P1, declines after P10, and remains at a relatively low level throughout adulthood. At E18, expressed in the forebrain, midbrain, and hindbrain. Within the forebrain, it is expressed in postmitotic cells of the cortical plate. At this stage, it can also be detected in other structures of central and peripheral nervous systems, including the trigeminal ganglion, superior cervical ganglion, retina and olfactory epithelium. Expression in the cortex is high at birth and declines substantially by P20. At P7, expressed in all cortical layers, and in the hippocampus, expression is high in the cell body layers of all subdivisions. Within the brain, expression decreases through development but continues to be expressed at high levels in the olfactory bulb, hippocampus, and cerebellum into adulthood. The MFD (multi-functional domain) domain is involved in transcription transactivation, nuclear body targeting and dimerization. Inhibits dendritic growth in cultured neurons. Belongs to the SS18 family.