TCR

Any of the proteins on the surface of T lymphocytes that enhance the response of the T-cell receptor to foreign antigens and stimulate signals from the receptor to the cytoplasm.

A cell membrane protein that mediates the effects of adrenergic stimulation on target organs by catecholamines.

A site in autonomic nerve pathways responsive to the adrenergic agents norepinephrine and epinephrine In general, alpha-1 receptors produce excitatory responses, and alpha-2 receptors produce inhibitory responses.

Receptors, primarily on white blood cells, that bind with the epitope on foreign antigens, stimulating an immune response.

One of the hair cells in the organ of Corti in the cochlea of the ear.

A site in autonomic nerve pathways responsive to the adrenergic agents norepinephrine and epinephrine. In general, beta-1 receptors produce excitatory responses, and beta-2 receptors produce inhibitory responses.

Any of the markers on T lymphocytes and other white blood cells that, along with major histocompatibility complex (MHC) genes, is responsible for the recognition of antigens. More than 100 receptor molecules have been identified. CD4 receptors on T4 lymphocytes are the sites to which HIV binds, producing infection.

Any of the cell membrane proteins or intracellular proteins that react with chemicals, e.g., hormones, circulating in the cell's environment. The reaction triggers the cell's characteristic response to the hormone or other chemical.

Any of several protein receptors for chemokines that spans the cell membrane and links to intracellular G proteins. The cell-to-cell signaling and regulating effects of chemokines, e.g., on inflammation or hematopoiesis, are mediated through chemokine receptors, which can be blocked with specific antagonist drugs. CCR5 and CXCR4 are chemokine receptors that are also receptors for HIV. The virus uses these receptors to gain entry into T cells, macrophages, and other CD4⁺ cells.

A site in a nerve synapse or effector cell that responds to the effect of acetylcholine.

A receptor on neutrophils, macrophages, lymphocytes, and other cells that allows complement factors to bind, thus stimulating inflammation, phagocytosis, and cell destruction.

A receptor that produces a sensation such as touch, temperature, or pain that can be localized in or on the surface of the body.

A receptor located in the skin.

A sense organ that responds to stimuli arising some distance from the body, such as the eye, ear, or nose.

Any of at least six receptors that bind dopamine in the brain. They influence body movements and emotional states. The dopamine receptors are designated D1, D2a, D2b, D3, D4, and D5. Each has an identifiably different function. The D2a receptor, for example, has a strong affinity for antipsychotic drugs, such as haloperidol.

A complex containing protein, located on a cell membrane, capable of being stimulated by drugs in the extracellular fluid, and translating that stimulation into an intracellular response. See: cell receptor

A cellular protein that binds female sex steroid hormones. When estrogens attach to it, they stimulate cells to transcribe DNA and manufacture proteins, typically leading to cellular growth and proliferation.

A receptor on phagocytes (neutrophils, monocytes, and macrophages) that binds Fc fragments of immunoglobulins G and E.

A macular hair cell of the utricle and saccule. It responds to changes in position of the head and linear acceleration.

An adhesion molecule on leukocytes that binds to endothelial cells in blood vessels. It is used by white blood cells to guide them to inflamed or infected tissues in the body.

A presynaptic receptor in the central nervous system that controls the release of histamine and other neurotransmitters, including acetylcholine, dopamine, and norepinephrine. It influences arousal and sleep, cognition, attention, and other body functions.

Any device used in radiology to detect the energy released by the imaging instrument after it passes through the imaged body part.

A receptor on the surface of white blood cells that identifies the type of cell and links with monokines, lymphokines, or other chemical mediators during the immune response.

A receptor on the surface of natural killer (NK) cells that bind with major histocompatibility complex (MHC) class I markers and inhibit the ability of NK cells to destroy target cells. Different groups of KIRs may create subsets of NK cells that bind to and destroy different targets.

Any of the bipolar nerve cells found in olfactory epithelium whose axons form olfactory nerve fibers.

A specific site on a cell surface that interacts in a highly selective fashion with opiate drugs. These receptors mediate the major known pharmacological actions and side effects of opiates and the functions of the endogenous opiate-like substances (endorphins and enkephalins).

A rod or cone cell of the retina.

A receptor on an antigen-presenting cell of the immune system that recognizes molecular sequences found on disease-causing organisms but not host cells. PRRs detect the presence of pathogen-associated chemicals such as lipopolysaccharides, mannans, and teichoic acids.

The antigen against which kidney-damaging antibodies are generated in membranous glomerulopathy.

A muscle or tendon spindle. These are the receptors for muscle stretching or kinesthetic stimuli.

Any of the hair cells in the cristae of the ampulla of the semicircular ducts of the ear. They are stimulated by angular acceleration or rotation.

The release channel for calcium ions that is found on the membranes of the sarcoplasmic reticulum of skeletal muscles.

A sensory nerve ending, a cell or group of cells, or a sense organ that when stimulated produces an afferent or sensory impulse.

Classification

Exteroreceptors are receptors located on or near the surface that respond to stimuli from the outside world. They include eye and ear receptors (for remote stimuli) and touch, temperature, and pain receptors (for contact). Interoceptors are those in the mucous linings of the respiratory and digestive tracts that respond to internal stimuli; also called visceroceptors. Proprioceptors are those responding to stimuli arising within body tissues.

Receptors also are classified according to the nature of stimuli to which they respond. These include chemoreceptors, which respond to chemicals (taste buds, olfactory cells, receptors in aortic and carotid bodies); pressoreceptors, which respond to pressure (receptors in the aortic and carotid sinuses); photoreceptors, which respond to light (rods and cones); and tactile receptors, which respond to touch (Meissner corpuscle).

A proteolytic enzyme that degrades extracellular soft tissues, thereby contributing to the invasiveness of a variety of cancers and infectious diseases. It has also been identified as a cause of focal segmental glomerulosclerosis.

A membrane-bound receptor expressed on the surfaces of cells that take up iron from the blood. Levels of this receptor are increased in iron-deficiency anemia. Measurement of circulating levels of the receptor are very useful in the diagnosis of iron deficiency in patients who also have anemia of chronic disease.

A proprioceptor located in a muscle or tendon that is stimulated by a stretch or pull.

A gustatory cell of a taste bud.

One of two polypeptide chains (a or ß) on the surface of T lymphocytes that recognize and bind foreign antigens. TCRs are antigen specific; their activity depends on antigen processing by macrophages or other antigen-presenting cells and the presence of major histocompatibility complex proteins to which peptides from the antigen are bound.

Any of the free nerve endings in the dermis that detect heat and cold.

Any of several receptors on macrophages and other immune and endothelial cells that reacts with pathogen components such as bacterial peptidoglycan or lipopolysaccharide. Activation of a receptor stimulates release of cytokines and other chemical signals that are part of innate immunity.

A sensory receptor that continues to trigger a response for minutes or hours after it is stimulated.

A Merkel disk, a Meissner corpuscle, or a nerve plexus around a hair root.

One of two polypeptide chains (a or ß) on the surface of T lymphocytes that recognize and bind foreign antigens. TCRs are antigen specific; their activity depends on antigen processing by macrophages or other antigen-presenting cells and the presence of major histocompatibility complex proteins to which peptides from the antigen are bound.

See also: receptor