amino acid sequence

DEFINITION:

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

aspartic acid

DEFINITION:

A nonessential amino acid, aminosuccinic acid, occurring in proteins; it is also an excitatory neurotransmitter in the central nervous system. Symbol Asp.

arginine

DEFINITION:

An amino acid produced by the hydrolysis or digestion of proteins.

tyrosine

DEFINITION:

A crystallizable, nonessential amino acid, ß-p-hydroxyphenylalanine, found in most proteins and synthesized metabolically from phenylalanine; it is a precursor of thyroid hormones, catecholamines, and melanin. Symbols Tyr and Y.

conserved

DEFINITION:

Kept from loss, decay, waste, or injury; preserved.

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.

GPCRs

DEFINITION:

G-protein-coupled receptors.

molecular

DEFINITION:

Of, pertaining to, or composed of molecules.

determinant

DEFINITION:

A factor that establishes the nature of an entity or event.

nephrogenic diabetes insipidus

DEFINITION:

A syndrome of polyuria and hyposthenuria caused by the failure of the renal tubules to reabsorb water in response to antidiuretic hormone, without disturbance in the renal filtration and solute excretion rates; the condition does not respond to exogenous vasopressin. It may be inherited as a rare X-linked trait or be acquired as a result of drug therapy or systemic disease.

vasopressin receptor

DEFINITION:

A molecular structure to which the hormone, vasopressin, binds. See also receptor .

arginine

DEFINITION:

An amino acid produced by the hydrolysis or digestion of proteins.

constitutively

DEFINITION:

Being produced constantly or in fixed amounts, regardless of environmental conditions or demand.

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.

G proteins

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., G_s stimulates and G_I inhibits enzyme activity.

constitutive

DEFINITION:

Produced constantly or in fixed amounts, regardless of environmental conditions or demand.

association

DEFINITION:

1. A state in which two attributes occur together either more or less often than expected by chance.

2. In neurology, a term applied to those regions of the brain that link the primary motor and sensory cortices; see association areas.

3. In genetics, the occurrence together of two or more phenotypic characteristics more often than would be expected by chance.

4. In psychiatry, a connection between ideas or feelings, especially between conscious thoughts and elements of the unconscious, or the formation of such a connection.

beta-arrestin

DEFINITION:

An inhibitory protein which blocks the receptor's ability to activate the stimulatory G protein G_s.

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.

localized

DEFINITION:

Not general; restricted to a limited region or to one or more spots.

wild-type

DEFINITION:

In genetics, the standard phenotype for any experimental organism; also a gene that determines a standard phenotypic trait. See also under gene .

receptors

DEFINITION:

See definitions under "receptor."

agonist

DEFINITION:

1. In anatomy, a prime mover.

2. In pharmacology, a drug that has affinity for and stimulateS physiologic activity at cell receptors normally stimulated by naturally occurring substances.

constitutively

DEFINITION:

Being produced constantly or in fixed amounts, regardless of environmental conditions or demand.

phenotype

DEFINITION:

1. The entire physical, biochemical, and physiological makeup of an individual as determined both genetically and environmentally, as opposed to genotype.
2. The expression of a single gene or gene pair.

paradigm

DEFINITION:

Model, pattern.

GPCRs

DEFINITION:

G-protein-coupled receptors.

arginine

DEFINITION:

An amino acid produced by the hydrolysis or digestion of proteins.

receptors

DEFINITION:

See definitions under "receptor."

G proteins

DEFINITION:

Any of a family of similar heterotrimeric proteins of the intracellular portion of the plasma membrane that bind activated receptor complexes and, through conformational changes and cyclic binding and hydrolysis of GTP, directly or indirectly effect alterations in channel gating and so couple cell surface receptors to intracellular responses. Some G proteins are named for their activities, e.g., G_s stimulates and G_I inhibits enzyme activity.

beta

DEFINITION:

[B, β] The second letter of the Greek alphabet.

As Beta - The beets, a genus of herbaceous plants of the family Chenopodiaceae. Beta vulgaris (L.) is the sugar beet, a commercial source of sucrose. The leafy tops of beets are rich in oxalates and can cause oxalate poisoning in animals that eat them in large amounts.

localized

DEFINITION:

Not general; restricted to a limited region or to one or more spots.

plasma membrane

DEFINITION:

The structure enveloping a cell, enclosing the cytoplasm, and forming a selective permeability barrier; it consists of lipids, proteins, and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees.

localization

DEFINITION:

1. The determination of the site or place of any process or lesion.
2. Restriction to a circumscribed or limited area.
3. Prelocalization.

alpha

DEFINITION:

1. The first letter of the Greek alphabet (A or α).

2. Something first; beginning.

arginine

DEFINITION:

An amino acid produced by the hydrolysis or digestion of proteins.

plasma membrane

DEFINITION:

The structure enveloping a cell, enclosing the cytoplasm, and forming a selective permeability barrier; it consists of lipids, proteins, and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees.

selective

DEFINITION:

Having a high degree of selectivity.

antagonists

DEFINITION:

1. Muscles whose actions are the direct opposite of that of other muscles.

endocytosis

DEFINITION:

The uptake by a cell of material from the environment by invagination (infolding) of its plasma membrane; it includes both phagocytosis and pinocytosis.

localization

DEFINITION:

1. The determination of the site or place of any process or lesion.
2. Restriction to a circumscribed or limited area.
3. Prelocalization.

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.

constitutive

DEFINITION:

Produced constantly or in fixed amounts, regardless of environmental conditions or demand.