Proteins accompanying the estrogen receptor alpha and beta: A model for studying protein hetero-complexes

Estro ! gen receptor a forms a highly dynamic protein complex in its activa ted and inactivated state. The protein is complexed with heat shock protein s and other accompanying proteins. Upon ligand binding these proteins are s hed off, the receptor dimerizes and forms a preinitiation complex with coac tivators and/or corepressors. A plethora of proteins has been discovered, a ssociated with this complex. These different proteins may either up- or dow n-regulate estrogen receptor-mediated transcription of target genes. Real t ime-biosensor technology is one approach to assessing these extremely dynam ic protein complex formations.