coupling

DEFINITION:

1. The joining together of two things.

2. In genetics, the occurrence on the same chromosome in a double heterozygote of the two mutant alleles of interest.

3. In cardiology, the serial occurrence of a normal heart beat followed closely by a premature beat.

selectivity

DEFINITION:

In pharmacology, the degree to which a dose of a drug produces the desired effect in relation to adverse effects.

G protein-coupled receptors

DEFINITION:

G protein-linked (or coupled) receptors mediate the cellular responses to an enormous diversity of signaling molecules, including hormones, neurotransmitters, and local mediators, which are as varied in structure as they are in function: the list includes proteins and small peptides, as well as amino acid and fatty acid derivatives.

Despite the chemical and functional diversity of the signaling molecules that bind to them, all of the G protein-linked receptors whose amino acid sequences are known from DNA sequencing studies have a similar structure and are almost certainly evolutionarily related. They consist of a single polypeptide chain that threads back and forth across the lipid bilayer seven times.

The members of this receptor family have conserved not only their amino acid sequence but also their functional relationship to G proteins by means of which they broadcast into the interior of the cell the message that an extracellular ligand is present.

peptide

DEFINITION:

Any member of a class of compounds of low molecular weight which yield two or more amino acids on hydrolysis. Formed by loss of water from the NH₂ and COOH groups of adjacent amino acids, they are known as di-, tri-, tetra- [etc.] peptides, depending on the number of amino acids in the molecule. Peptides form the constituent parts of proteins.

ligands

DEFINITION:

1. Molecules that bind to other molecules, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme.
2. Molecules that donate or accept a pair of electrons to form coordinate covalent bonds with the central metal atom of a coordination complex.

coupled

DEFINITION:

See coupling.

V2

DEFINITION:

Vasopressin-2. See vasopressin-2 gene and vasopressin-2 receptor.

vasopressin

DEFINITION:

1. One of two octapeptide hormones formed by the neuronal cells of the hypothalamic nuclei and stored in the posterior lobe of the pituitary gland (neurohypophysis), the other being oxytocin. It stimulates the contraction of the muscular tissue of the capillaries and arterioles, raising the blood pressure. It promotes contraction of the intestinal musculature and increases peristalsis, and also exerts some contractile influence on the uterus. It also has a specific effect on the epithelial cells of the distal portion of the uriniferous tubule, augmenting resorption of water independently of solutes, resulting in concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma.

2. [USP], A pharmaceutical preparation of the same principle, prepared synthetically or obtained from the posterior pituitary of healthy domestic animals used for food by man; used mainly as an antidiuretic in the treatment of acute or chronic diabetes insipidus, administered intramuscularly as a test of hypothalamo-neurohypophysial-renal function in distinguishing central from nephrogenic diabetes insipidus; it may also be used to stimulate smooth muscle tissue, especially to induce vasoconstriction in the presence of hemorrhage. Called also antidiuretic hormone (ADH).

peptide

DEFINITION:

Any member of a class of compounds of low molecular weight which yield two or more amino acids on hydrolysis. Formed by loss of water from the NH₂ and COOH groups of adjacent amino acids, they are known as di-, tri-, tetra- [etc.] peptides, depending on the number of amino acids in the molecule. Peptides form the constituent parts of proteins.

receptors

DEFINITION:

See definitions under "receptor."

model

DEFINITION:

1. Something that represents or simulates something else; a replica.
2. A reasonable facsimile of the body or any of its parts; used for demonstration and teaching purposes.
3. Cast, definition 5.
4. To imitate another's behavior; See modeling .
5. A hypothesis or theory.

V2 receptor

DEFINITION:

See under receptor .

V2 receptor

DEFINITION:

See under receptor .

amino acids

DEFINITION:

See definition for "amino acid."

mediate

DEFINITION:

Indirect; accomplished by the aid of an intervening medium.

hormone

DEFINITION:

A product of living cells that circulates in body fluids and produces a specific effect on the activity of cells remote from its point of origin; especially: one exerting a stimulatory effect on a cellular activity.

hypophysiotropic hormones - Hormones produced by the hypothalamus, usually releasing hormones (see below), which maintain the endocrine functions of cells of the adenohypophysis.

neurohormone - A hormone secreted by a specialized neuron into the bloodstream, the cerebrospinal fluid, or the intercellular spaces of the nervous system.

releasing hormones - Hormones elaborated in one structure that cause the release of hormones from another structure, such as those from the hypothalamus that act on the adenohypophysis. The term is applied to substances of established chemical identity, whereas substances of unknown chemical structure are called releasing factors .

cAMP

DEFINITION:

Cyclic AMP (cyclic adenosine monophosphate).

hormone

DEFINITION:

A product of living cells that circulates in body fluids and produces a specific effect on the activity of cells remote from its point of origin; especially: one exerting a stimulatory effect on a cellular activity.

hypophysiotropic hormones - Hormones produced by the hypothalamus, usually releasing hormones (see below), which maintain the endocrine functions of cells of the adenohypophysis.

neurohormone - A hormone secreted by a specialized neuron into the bloodstream, the cerebrospinal fluid, or the intercellular spaces of the nervous system.

releasing hormones - Hormones elaborated in one structure that cause the release of hormones from another structure, such as those from the hypothalamus that act on the adenohypophysis. The term is applied to substances of established chemical identity, whereas substances of unknown chemical structure are called releasing factors .

intracellular cAMP

DEFINITION:

Cyclic adenosine monophosphate within a cell.

functional analysis

DEFINITION:

Determining the function or characteristic behaviors of component parts of a substance.

mutant receptors

DEFINITION:

Molecular structures within or on the surface of cells which do not bind with the specific substance for which they are intended, or do not cause the specific physiologic effect that accompanies that binding. See receptor.

transiently

DEFINITION:

1. A: passing especially quickly into and out of existence: transitory. B: passing through or by a place with only a brief stay or sojourn.

2. Affecting something or producing results beyond itself.

expressed

DEFINITION:

1. Showing a detectable effect of a gene.

2. Made known; shown.

3. Squeezed out; extracted by pressing.

V2 receptor

DEFINITION:

See under receptor .

sequence

DEFINITION:

1. A connected series of events or things.
2. In dysmorphology, a pattern of multiple anomalies derived from a single known or presumed prior anomaly or mechanical factor.
3. In molecular biology, often used to refer to DNA having a particular nucleotide composition or occurring in a particular region of the genome.

third intracellular loop

DEFINITION:

See schematic drawing of the V2R.

activation

DEFINITION:

1. The act or process of rendering active.

2. The transformation of a proenzyme into an active enzyme by the action of a kinase or another proenzyme.

3. Gain in the purifying of sewage by means of activated sludge.

4. The process by which the central nervous system is stimulated into activity through the mediation of the reticular activating system.

5. The deliberate induction of a pattern of electrical activity in the brain in electroencephalography.

receptor

DEFINITION:

1. A molecular structure within a cell or on the surface characterized by (1) selective binding of a specific substance and (2) a specific physiologic effect that accompanies the binding, e.g., membrane receptors for peptide hormones, neurotransmitters, antigens, complement fragments, and immunoglobulins and nuclear receptors for steroid hormones.

2. A sensory nerve terminal that responds to stimuli of various kinds; classified in various ways including by the type of stimulus and by the location in the body.

V2 receptor - The structure to which the antidiuretic hormone, arginine vasopressin binds.

polar

DEFINITION:

1. Of or pertaining to a pole (as of a magnet).

2. Of or relating to a geographical pole.

3. Being at opposite ends of a spectrum of manifestations, as polar forms of leprosy.

V2 receptor

DEFINITION:

See under receptor .

residues

DEFINITION:

1. That which remains after the removal of other substances.
2. In biochemistry, the portion of a molecule that remains after it has lost some of its components, as an amino acid residue, which loses a water molecule when it is joined to another amino acid.

sequence

DEFINITION:

1. A connected series of events or things.
2. In dysmorphology, a pattern of multiple anomalies derived from a single known or presumed prior anomaly or mechanical factor.
3. In molecular biology, often used to refer to DNA having a particular nucleotide composition or occurring in a particular region of the genome.

V2

DEFINITION:

Vasopressin-2. See vasopressin-2 gene and vasopressin-2 receptor.

coupling

DEFINITION:

1. The joining together of two things.

2. In genetics, the occurrence on the same chromosome in a double heterozygote of the two mutant alleles of interest.

3. In cardiology, the serial occurrence of a normal heart beat followed closely by a premature beat.

selectivity

DEFINITION:

In pharmacology, the degree to which a dose of a drug produces the desired effect in relation to adverse effects.

novel

DEFINITION:

Of a new kind, or different from anything seen or known before.

V2

DEFINITION:

Vasopressin-2. See vasopressin-2 gene and vasopressin-2 receptor.

coupling

DEFINITION:

1. The joining together of two things.

2. In genetics, the occurrence on the same chromosome in a double heterozygote of the two mutant alleles of interest.

3. In cardiology, the serial occurrence of a normal heart beat followed closely by a premature beat.

third intracellular loop

DEFINITION:

See schematic drawing of the V2R.

amino acid sequence

DEFINITION:

The sequence of amino acid residues in the polypeptides synthesized by living organisms. See also genetic code and amino acid.

domain

DEFINITION:

A compact globular structure composed of one section of a polypeptide chain that constitutes a recognizable unit of the tertiary structure of a protein. Domains may fold up independently and maintain their native conformation when the connecting sections of the chain are broken.

novel

DEFINITION:

Of a new kind, or different from anything seen or known before.

peptide

DEFINITION:

Any member of a class of compounds of low molecular weight which yield two or more amino acids on hydrolysis. Formed by loss of water from the NH₂ and COOH groups of adjacent amino acids, they are known as di-, tri-, tetra- [etc.] peptides, depending on the number of amino acids in the molecule. Peptides form the constituent parts of proteins.

protein

DEFINITION:

Any of a group of complex organic compounds which contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur, the characteristic element being nitrogen, and which are widely distributed in plants and animals. Proteins, the principal constituents of the protoplasm of all cells, are of high molecular weight and consist essentially of combinations of a-amino acids in peptide linkages. Twenty different amino acids are commonly found in proteins, and each protein has a unique, genetically defined amino acid sequence which determines its specific shape and function. They serve as enzymes, structural elements, hormones, immunoglobulins, etc., and are involved in oxygen transport, muscle contraction, electron transport, and other activities throughout the body, and in photosynthesis.

binding protein - any of a number of plasma proteins (See below) that bind to hormones of low solubility (chiefly the thyroid and steroid hormones), thus providing a transport system for them; some are specific for particular hormones, while others bind to any sparingly soluble hormones. Called also carrier protein or transport protein (See below).

carrier proteins - A binding protein (See above).

plasma proteins - The hundreds of different proteins present in blood plasma, including carrier proteins (such as albumin, transferrin, and haptoglobin), fibrinogen and other coagulation factors, complement components, immunoglobulins, enzyme inhibitors, precursors of substances such as angiotensin and bradykinin, and many other types of proteins.

transport protein - binding protein (See above).

coupling

DEFINITION:

1. The joining together of two things.

2. In genetics, the occurrence on the same chromosome in a double heterozygote of the two mutant alleles of interest.

3. In cardiology, the serial occurrence of a normal heart beat followed closely by a premature beat.

selectivity

DEFINITION:

In pharmacology, the degree to which a dose of a drug produces the desired effect in relation to adverse effects.

permission

DEFINITION:

Formal consent; authorization.