Receptorok

Receptorok are proteins that detect signaling molecules and translate their binding into cellular responses. They can be located on the cell surface or inside the cell and show high specificity for their ligands, such as hormones, neurotransmitters, growth factors, or environmental chemicals. The interaction typically follows a lock-and-key or induced-fit mechanism, and binding often alters the receptor’s conformation to initiate a signal transduction cascade.

Major classes of cell-surface receptorok include G protein–coupled receptors (GPCRs), receptor tyrosine kinases (RTKs), ligand-gated ion channels, and cytokine receptors. Intracellular receptorok, such as steroid hormone receptors, reside in the cytoplasm or nucleus and regulate gene expression after ligand binding. In all cases, receptor activation converts extracellular information into intracellular signals, often via second messengers like cyclic AMP, calcium ions, inositol trisphosphate, or lipid-derived mediators, or through phosphorylation cascades.

Receptorok are tightly regulated by synthesis, trafficking, desensitization, internalization, and degradation. Upregulation or downregulation of receptorok levels can adjust cell sensitivity to signals. Dysregulation, mutation, or overexpression of receptors is linked to various diseases, including metabolic disorders, cancer, and neurological conditions.

Pharmacology frequently targets receptorok with agonists, antagonists, or allosteric modulators to treat disease or influence physiology. Experimental approaches to studying receptorok include radioligand binding assays, immunodetection, and genetic models such as knockout or knock-in organisms.