Question

Give an example of a specific intracellular receptor be sure to indicate its exact location and function. (2pts)

Answer 1

Intracellular receptors are receptors that are located in the inside the cell rather than on cell membrane. The ligand has to bypass the cell membrane to bind to these receptors.

Example is the nuclear steroid hormone receptor or the inositol 3 phosphate (IP3) receptor. Nuclear steroid hormone receptors (nuclear estrogen/ progesterone receptors) are present in cytoplasm and nucleus of cell. IP3 receptor is present on Endoplasmic reticulum.

Nuclear steroid hormone receptors for estrogen or progesterone are present in nucleus or cytoplasm when there is no ligand (steroid hormone estrogen/progesterone). Steroid hormones diffuse through the plasma membrane and bind to the intracellular receptor. The receptor undergoes a conformational change and can dimerize. The receptor-hormone complex then enters the nucleus, where the receptor binds to the DNA at specific hormone response elements present in genes. This cause activation of specific target genes.

Intracellular steroid hormone receptors have both hormone binding and DNA binding domains.