hormonareceptor

Hormonareceptor, or hormone receptor, is a cellular protein that binds a hormone and translates this binding into a functional response. Receptors are highly specific for their ligands and can be located on the cell surface or inside the cell.

Cell-surface receptors bind hydrophilic hormones such as peptides and amines; they include G protein-coupled receptors, receptor tyrosine kinases, and ion-channel receptors. Intracellular receptors bind lipophilic hormones such as steroids and thyroid hormones; these receptors are typically located in the cytoplasm or nucleus and often act as transcription factors.

Upon ligand binding, receptors undergo conformational changes that trigger signaling cascades (for example, cAMP, IP3/DAG, MAPK pathways) or direct regulation of gene expression. Nuclear receptors may regulate gene transcription by binding to hormone response elements and recruiting co-regulators.

Understanding hormone receptors is central to endocrinology and pharmacology. Alterations in receptor number, affinity, or signaling can contribute to disease, and many drugs act by modulating receptor activity, including agonists, antagonists, and selective receptor modulators. Examples include estrogen receptors in breast cancer and the insulin receptor in diabetes.