chromaffin granule lumen
Definition
Target type: cellularcomponent
The volume enclosed by the membrane of a chromaffin granule. [GOC:rph]
The chromaffin granule lumen is the internal space of chromaffin granules, which are specialized secretory vesicles found in the cytoplasm of chromaffin cells in the adrenal medulla. These granules store and release catecholamines, primarily epinephrine (adrenaline) and norepinephrine (noradrenaline), in response to neuronal stimulation. The lumen of the chromaffin granule is a complex environment containing a high concentration of catecholamines, along with various proteins, enzymes, and other molecules that contribute to the synthesis, storage, and release of these hormones.
**Key Components of the Chromaffin Granule Lumen:**
* **Catecholamines:** The primary cargo of chromaffin granules, epinephrine and norepinephrine, are stored in the lumen at high concentrations (up to 0.5 M). These catecholamines are synthesized by the chromaffin cells and packaged into the granules.
* **Chromogranins:** These acidic proteins form a complex with catecholamines, contributing to their storage and preventing their premature release. Chromogranins also serve as precursors to bioactive peptides.
* **Enzymes:** Several enzymes are present in the lumen, including dopamine beta-hydroxylase (DBH), which catalyzes the conversion of dopamine to norepinephrine; phenylethanolamine N-methyltransferase (PNMT), which converts norepinephrine to epinephrine; and other enzymes involved in the metabolism of catecholamines.
* **ATP:** Adenosine triphosphate (ATP) is present in the lumen and contributes to the electrochemical gradient that drives the release of catecholamines during exocytosis.
* **Other Proteins:** Several other proteins are found in the chromaffin granule lumen, including:
* **Secretory carrier membrane protein 2 (SCAMP2):** Involved in vesicle trafficking and exocytosis.
* **Synaptotagmin-like protein 1 (SYTL1):** Plays a role in calcium-dependent exocytosis.
* **Neuropeptides:** Small peptide hormones that are co-stored and co-released with catecholamines.
**Physiological Significance:**
The chromaffin granule lumen is essential for the proper synthesis, storage, and release of catecholamines. The unique composition of the lumen, including the high concentration of catecholamines and other components, provides the optimal environment for these processes. Exocytosis of the chromaffin granule, triggered by neuronal stimulation, releases catecholamines into the bloodstream, where they act on target organs to regulate a wide range of physiological functions, including heart rate, blood pressure, and stress response.'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Dopamine beta-hydroxylase | A dopamine beta-hydroxylase that is encoded in the genome of cow. [OMA:P15101, PRO:DNx] | Bos taurus (cattle) |
| Dopamine beta-hydroxylase | A dopamine beta-hydroxylase that is encoded in the genome of human. [PRO:DNx, UniProtKB:P09172] | Homo sapiens (human) |
Compounds (12)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| fusaric acid | Fusaric Acid: A picolinic acid derivative isolated from various Fusarium species. It has been proposed for a variety of therapeutic applications but is primarily used as a research tool. Its mechanisms of action are poorly understood. It probably inhibits DOPAMINE BETA-HYDROXYLASE, the enzyme that converts dopamine to norepinephrine. It may also have other actions, including the inhibition of cell proliferation and DNA synthesis. | aromatic carboxylic acid; pyridines | |
| hypericin | |||
| tyramine | monoamine molecular messenger; primary amino compound; tyramines | EC 3.1.1.8 (cholinesterase) inhibitor; Escherichia coli metabolite; human metabolite; mouse metabolite; neurotransmitter | |
| tropolone | tropolone : A cyclic ketone that is cyclohepta-2,4,6-trien-1-one substituted by a hydroxy group at position 2. It is a toxin produced by the agricultural pathogen Burkholderia plantarii. Tropolone: A seven-membered aromatic ring compound. It is structurally related to a number of naturally occurring antifungal compounds (ANTIFUNGAL AGENTS). | alpha-hydroxy ketone; cyclic ketone; enol | bacterial metabolite; fungicide; toxin |
| 3-phenylpropylamine | 3-phenylpropylamine : A phenylalkylamine that is benzene in which one of the hydrogens is substituted by a 3-aminopropyl group. | benzenes; phenylalkylamine; primary amino compound | |
| u 0521 | U 0521: catechol methyltransferase antagonist; structure | acetophenones | |
| 7-hydroxytropolone | 7-hydroxytropolone: structure | ||
| 4-vinylphenol | 4-hydroxystyrene : A member of the class of phenols that is styrene carrying a hydroxy substituent at position 4. 4-vinylphenol: RN given refers to cpd with locants as specified | phenols | human urinary metabolite; human xenobiotic metabolite |
| 3,7-dihydroxytropolone | 3,7-dihydroxytropolone : A cyclic ketone that is tropolone in which the hydrogens at positions 3 and 7 are substituted by hydroxy groups. It is isolated from the soil bacterium Streptomyces tropolofaciens strain K611-97. 3,7-dihydroxytropolone: from Streptomyces tropolofaciens; active against B16 melanoma; structure given in first source | alpha-hydroxy ketone; cyclic ketone; enol; triol | antineoplastic agent; bacterial metabolite |
| methimazole | methimazole : A member of the class of imidazoles that it imidazole-2-thione in which a methyl group replaces the hydrogen which is attached to a nitrogen. Methimazole: A thioureylene antithyroid agent that inhibits the formation of thyroid hormones by interfering with the incorporation of iodine into tyrosyl residues of thyroglobulin. This is done by interfering with the oxidation of iodide ion and iodotyrosyl groups through inhibition of the peroxidase enzyme. | 1,3-dihydroimidazole-2-thiones | antithyroid drug |
| 1-(4-hydroxybenzyl)imidazole-2-thiol | 1-(4-hydroxybenzyl)imidazole-2-thiol: RN & structure given in first source; RN not in Chemline 3/87 | ||
| sk&f 102698 |