chromaffin granule membrane
Definition
Target type: cellularcomponent
The lipid bilayer surrounding a chromaffin granule, a specialized secretory vesicle found in the cells of adrenal glands and various other organs, which is concerned with the synthesis, storage, metabolism, and secretion of epinephrine and norepinephrine. [GOC:jl]
The chromaffin granule membrane is a specialized cellular component that encapsulates neurotransmitters, primarily catecholamines like epinephrine and norepinephrine, within chromaffin cells of the adrenal medulla. It is a complex structure composed of various proteins and lipids, each playing a crucial role in the storage, release, and regulation of these neurotransmitters. The membrane is characterized by a high density of proteins, including:
* **Chromogranins:** These acidic proteins are responsible for binding and condensing neurotransmitters within the granule, ensuring their efficient storage. They also play a role in the regulated release of neurotransmitters upon stimulation.
* **Synaptotagmin:** This protein acts as a calcium sensor, mediating the fusion of the chromaffin granule membrane with the plasma membrane during exocytosis. This fusion allows the release of neurotransmitters into the synaptic cleft.
* **V-ATPase:** This proton pump actively transports protons into the granule lumen, maintaining an acidic pH environment crucial for the proper storage and stability of neurotransmitters.
* **Catecholamine transporters:** These membrane proteins facilitate the uptake of catecholamines into the granule, ensuring their efficient accumulation.
* **Other regulatory proteins:** Several other proteins, including kinases, phosphatases, and adaptor proteins, participate in the complex signaling pathways that control the synthesis, storage, and release of neurotransmitters.
The lipid composition of the chromaffin granule membrane is also significant. It contains a high proportion of phospholipids, including phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin, which contribute to the structural integrity and fluidity of the membrane. Cholesterol, a major component of the membrane, plays a critical role in regulating membrane fluidity and permeability.
The unique structure and composition of the chromaffin granule membrane ensure the efficient storage, regulated release, and precise targeting of neurotransmitters, enabling chromaffin cells to rapidly respond to various physiological stimuli. This complex cellular component plays a vital role in the body's stress response and the regulation of various physiological processes.'
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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 |