Two Protocols to Study the Interactions of Thyroid Hormone Receptors with Other Proteins and Chromatin

Understanding the transcriptional function of thyroid hormone receptors implies a precise analysis of their interactions with chromatin and other protein components of the cells. We present here two protocols that are routinely used in our laboratory. The first co-immunoprecipitation procedure allows addressing the capacity of proteins to form stable multiprotein complexes with TRs in cells. The chromatin affinity purification enables us to define the sites occupied by TRs on chromatin. In this case the lack of high quality antibodies is circumvented by introducing an N-terminal tag in TR, with unspecific affinity for immunoglobulins.