Complex sentence: When triiodothyronine (T3) binds a thyroid hormone receptor (TR), it induces a conformational change in the TR which displaces the corepressor from the receptor/DNA complex, resulting in recruitment of coactivator proteins and RNA polymerase, activating transcription of the gene.
Split into simpler sentences: When triiodothyronine (T3) binds a receptor, it induces a conformational change in the receptor, displacing the corepressor from the complex. This leads to recruitment of coactivator proteins and RNA polymerase, activating transcription of the gene.