Nuclear Receptors

Nuclear receptors are a class of proteins responsible for sensing steroids, thyroid hormones, vitamins, and certain other molecules.Nuclear receptors are specific to animals and are not found in protists, algae, fungi, or plants. There are 47 nuclear receptors in humans.These intracellular receptors work with other proteins to regulate the expression of specific genes thereby controlling the development, homeostasis, and metabolism of the organism. A unique property of nuclear receptors that differentiates them from other classes of receptors is their direct control of genomic DNA. Hence these receptors are classified as transcription factors. The regulation of gene expression by nuclear receptors often occurs in the presence of a ligand. Ligand binding to a nuclear receptor results in a conformational change activating the receptor. The result is up-or down-regulation of gene expression. Nuclear receptors play key roles in both embryonic development and adult homeostasis.