TRβ1 also known as TR beta 1, THRB is a member of the thyroid hormone nuclear receptor family, plays a crucial role in mediating the effects of thyroid hormones on gene expression, which is vital for regulating metabolic processes, growth, and development. TRβ1 is primarily located in the nucleus, where TRβ1 functions as a ligand-dependent transcription factor, binding to thyroid hormone response elements (TREs) to modulate the transcription of target genes. Nuclear localization of TRβ1 is essential because TRβ1 allows for direct interaction with DNA and other transcriptional machinery, thereby influencing cellular responses to thyroid hormones. TRβ1 can form heterodimers with retinoid X receptors, enhancing transcriptional activity and allowing for a more nuanced regulation of gene expression in response to thyroid hormone levels.