Target type: biologicalprocess
The process by which an organelle membrane interacts with another membrane via molecular tethers that physically bridge the two membranes and attach them to each other. [PMID:27875684]
Organelle localization by membrane tethering is a crucial process for maintaining cellular organization and function. It involves the specific targeting and anchoring of organelles to particular regions of the cell, often at membrane contact sites (MCSs) where different organelles come into close proximity. This process relies on a complex interplay of proteins, lipids, and other factors, ensuring precise positioning of organelles for efficient communication and exchange of molecules.
Here is a detailed breakdown of the biological process of organelle localization by membrane tethering:
1. **Protein-Protein Interactions:** Membrane tethering proteins, often possessing long coiled-coil domains, act as molecular bridges connecting specific organelles. These tethers can be either directly linked to the organelle membrane or indirectly associated through intermediary proteins. These interactions are highly selective, ensuring that the correct organelles are brought together.
2. **Lipid Bilayer Interactions:** The tethering proteins can also interact directly with specific lipids present in the organelle membranes. This interaction contributes to the specificity of organelle localization, allowing tethers to recognize and bind to the appropriate membranes.
3. **Membrane Curvature:** The shape and curvature of organelle membranes can also play a role in tethering. Some tethers are specifically adapted to recognize and bind to curved membranes, facilitating the interaction of organelles with specific shapes.
4. **Signal Transduction:** The tethering process can be regulated by signaling pathways, allowing for dynamic adjustments in organelle positioning based on cellular needs. These pathways can involve phosphorylation, dephosphorylation, or other post-translational modifications of tethering proteins.
5. **Functional Consequences:** Precise organelle localization via membrane tethering is critical for various cellular functions, including:
- **Metabolic Exchange:** Tethering enables the exchange of metabolites and signaling molecules between organelles, supporting interconnected metabolic pathways.
- **Membrane Trafficking:** Tethering facilitates the efficient movement of vesicles and other membrane-bound compartments between organelles.
- **Signal Transduction:** Tethering brings signaling proteins into close proximity, enabling efficient signal relay and cellular responses.
- **Organelle Dynamics:** Tethering can influence the shape and movement of organelles, contributing to dynamic cellular structures.
6. **Examples:** Numerous examples of membrane tethering proteins have been identified, each involved in the localization of specific organelles:
- **ER-Golgi tethering:** Proteins like the golgins and p115 facilitate the movement of vesicles between the endoplasmic reticulum (ER) and the Golgi apparatus.
- **Mitochondria-ER tethering:** Proteins like Mfn1/2 and mitofusin-2 tether mitochondria to the ER, enabling calcium exchange and metabolic regulation.
- **Peroxisome-ER tethering:** Pex14p and Pex17p are involved in the tethering of peroxisomes to the ER, facilitating protein import and lipid metabolism.
7. **Disruption of Tethering:** Dysregulation of tethering processes can lead to cellular dysfunction and disease. Defects in tethering proteins or their regulatory pathways have been implicated in various diseases, including metabolic disorders, neurodegenerative diseases, and cancer.
In conclusion, organelle localization by membrane tethering is a complex and crucial process that plays a vital role in cellular organization and function. It involves the orchestrated interplay of tethering proteins, lipids, and signaling pathways, ensuring the precise positioning of organelles for efficient communication, metabolism, and overall cellular homeostasis.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Sarcoplasmic/endoplasmic reticulum calcium ATPase 2 | A sarcoplasmic/endoplasmic reticulum calcium ATPase 2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P16615] | Homo sapiens (human) |
| Calmodulin-1 | A calmodulin (human) that is a translation product of the CALM1 gene. [PRO:DAN, UniProtKB:P0DP23] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| 2,5-di-tert-butylhydroquinone | 2,5-di-tert-butylbenzene-1,4-diol : A member of the class of hydroquinones that is benzene-1,4-diol substituted by tert-butyl groups at position 2 and 5. | hydroquinones | |
| chlorpromazine | chlorpromazine : A substituted phenothiazine in which the ring nitrogen at position 10 is attached to C-3 of an N,N-dimethylpropanamine moiety. Chlorpromazine: The prototypical phenothiazine antipsychotic drug. Like the other drugs in this class chlorpromazine's antipsychotic actions are thought to be due to long-term adaptation by the brain to blocking DOPAMINE RECEPTORS. Chlorpromazine has several other actions and therapeutic uses, including as an antiemetic and in the treatment of intractable hiccup. | organochlorine compound; phenothiazines; tertiary amine | anticoronaviral agent; antiemetic; dopaminergic antagonist; EC 3.4.21.26 (prolyl oligopeptidase) inhibitor; phenothiazine antipsychotic drug |
| promethazine | promethazine : A tertiary amine that is a substituted phenothiazine in which the ring nitrogen at position 10 is attached to C-3 of an N,N-dimethylpropan-2-amine moiety. Promethazine: A phenothiazine derivative with histamine H1-blocking, antimuscarinic, and sedative properties. It is used as an antiallergic, in pruritus, for motion sickness and sedation, and also in animals. | phenothiazines; tertiary amine | anti-allergic agent; anticoronaviral agent; antiemetic; antipruritic drug; H1-receptor antagonist; local anaesthetic; sedative |
| trifluoperazine | N-alkylpiperazine; N-methylpiperazine; organofluorine compound; phenothiazines | antiemetic; calmodulin antagonist; dopaminergic antagonist; EC 1.8.1.12 (trypanothione-disulfide reductase) inhibitor; EC 5.3.3.5 (cholestenol Delta-isomerase) inhibitor; phenothiazine antipsychotic drug | |
| diphenylmethane | diphenylmethane : A diarylmethane that is methane substituted by two phenyl groups. | diarylmethane | |
| hesperidin | hesperidin : A disaccharide derivative that consists of hesperetin substituted by a 6-O-(alpha-L-rhamnopyranosyl)-beta-D-glucopyranosyl moiety at position 7 via a glycosidic linkage. Hesperidin: A flavanone glycoside found in CITRUS fruit peels. | 3'-hydroxyflavanones; 4'-methoxyflavanones; dihydroxyflavanone; disaccharide derivative; flavanone glycoside; monomethoxyflavanone; rutinoside | mutagen |
| flavone | flavone : The simplest member of the class of flavones that consists of 4H-chromen-4-one bearing a phenyl substituent at position 2. flavone: RN given refers to unlabeled cpd; structure given in first source | flavones | metabolite; nematicide |
| 3-hydroxyflavone | 3-hydroxyflavone: structure given in first source flavonol : A monohydroxyflavone that is the 3-hydroxy derivative of flavone. | flavonols; monohydroxyflavone | |
| 6-hydroxyflavone | 6-hydroxyflavone: antioxidant; structure in first source | hydroxyflavonoid | |
| paxilline | paxilline : An indole diterpene alkaloid with formula C27H33NO4 isolated from Penicillium paxilli. It is a potent inhibitor of large conductance Ca2(+)- and voltage-activated K(+) (BK)-type channels. paxilline: structure given in first source; RN given refers to (2R-(2alpha,4bbeta,6aalpha,12bbeta,12calpha,14abeta))-isomer | diterpene alkaloid; enone; organic heterohexacyclic compound; terpenoid indole alkaloid; tertiary alcohol | anticonvulsant; Aspergillus metabolite; EC 3.6.3.8 (Ca(2+)-transporting ATPase) inhibitor; genotoxin; geroprotector; mycotoxin; Penicillium metabolite; potassium channel blocker |
| naringenin | (S)-naringenin : The (S)-enantiomer of naringenin. | (2S)-flavan-4-one; naringenin | expectorant; plant metabolite |
| curcumin | curcumin : A beta-diketone that is methane in which two of the hydrogens are substituted by feruloyl groups. A natural dyestuff found in the root of Curcuma longa. Curcumin: A yellow-orange dye obtained from tumeric, the powdered root of CURCUMA longa. It is used in the preparation of curcuma paper and the detection of boron. Curcumin appears to possess a spectrum of pharmacological properties, due primarily to its inhibitory effects on metabolic enzymes. | aromatic ether; beta-diketone; diarylheptanoid; enone; polyphenol | anti-inflammatory agent; antifungal agent; antineoplastic agent; biological pigment; contraceptive drug; dye; EC 1.1.1.205 (IMP dehydrogenase) inhibitor; EC 1.1.1.21 (aldehyde reductase) inhibitor; EC 1.1.1.25 (shikimate dehydrogenase) inhibitor; EC 1.6.5.2 [NAD(P)H dehydrogenase (quinone)] inhibitor; EC 1.8.1.9 (thioredoxin reductase) inhibitor; EC 2.7.10.2 (non-specific protein-tyrosine kinase) inhibitor; EC 3.5.1.98 (histone deacetylase) inhibitor; flavouring agent; food colouring; geroprotector; hepatoprotective agent; immunomodulator; iron chelator; ligand; lipoxygenase inhibitor; metabolite; neuroprotective agent; nutraceutical; radical scavenger |
| quercetin | 7-hydroxyflavonol; pentahydroxyflavone | antibacterial agent; antineoplastic agent; antioxidant; Aurora kinase inhibitor; chelator; EC 1.10.99.2 [ribosyldihydronicotinamide dehydrogenase (quinone)] inhibitor; geroprotector; phytoestrogen; plant metabolite; protein kinase inhibitor; radical scavenger | |
| chrysin | chrysin : A dihydroxyflavone in which the two hydroxy groups are located at positions 5 and 7. | 7-hydroxyflavonol; dihydroxyflavone | anti-inflammatory agent; antineoplastic agent; antioxidant; EC 2.7.11.18 (myosin-light-chain kinase) inhibitor; hepatoprotective agent; plant metabolite |
| 7-hydroxyflavone | 7-hydroxyflavone : A hydroxyflavonoid in which the flavone nucleus is substituted at position 7 by a hydroxy group. | hydroxyflavonoid | |
| shamixanthone | shamixanthone : A pyranoxanthene that is 2,3-dihydropyrano[3,2-a]xanthen-12(1H)-one bearing hydroxy substituents at positions 1 and 11 as well as a prop-1-en-2-yl group at position 2, a methyl substituent at position 5 and a 3,3-dimethylallyl group at position 8. A secondary metabolite produced by Aspergillus nidulans. | cyclic ketone; phenols; pyranoxanthene | metabolite |
| biselyngbyaside | biselyngbyaside: antineoplastic from the marine cyanobacterium Lyngbya sp.; structure in first source | ||
| clozapine | clozapine : A benzodiazepine that is 5H-dibenzo[b,e][1,4]diazepine substituted by a chloro group at position 8 and a 4-methylpiperazin-1-yl group at position 11. It is a second generation antipsychotic used in the treatment of psychiatric disorders like schizophrenia. Clozapine: A tricylic dibenzodiazepine, classified as an atypical antipsychotic agent. It binds several types of central nervous system receptors, and displays a unique pharmacological profile. Clozapine is a serotonin antagonist, with strong binding to 5-HT 2A/2C receptor subtype. It also displays strong affinity to several dopaminergic receptors, but shows only weak antagonism at the dopamine D2 receptor, a receptor commonly thought to modulate neuroleptic activity. Agranulocytosis is a major adverse effect associated with administration of this agent. | benzodiazepine; N-arylpiperazine; N-methylpiperazine; organochlorine compound | adrenergic antagonist; dopaminergic antagonist; EC 3.4.21.26 (prolyl oligopeptidase) inhibitor; environmental contaminant; GABA antagonist; histamine antagonist; muscarinic antagonist; second generation antipsychotic; serotonergic antagonist; xenobiotic |
| alpha-cyclopiazonic acid | alpha-cyclopiazonic acids |