junctional sarcoplasmic reticulum membrane
Definition
Target type: cellularcomponent
The part of the sarcoplasmic reticulum membrane that contains calcium release channels, is devoted to calcium release and is juxtaposed to transverse tubule membrane. The junctional sarcoplasmic reticulum membrane consists of the junctional region of the terminal cisterna membrane. [GOC:mtg_muscle]
The junctional sarcoplasmic reticulum (jSR) membrane is a specialized domain of the sarcoplasmic reticulum (SR) that directly interacts with the transverse tubules (T-tubules) of skeletal muscle fibers. This close proximity allows for rapid and efficient calcium signaling during muscle contraction.
The jSR membrane is characterized by several key features:
* **Presence of junctional feet:** These protein complexes, also known as ryanodine receptors (RyRs), are embedded in the jSR membrane and project into the T-tubule lumen. They serve as calcium release channels, releasing calcium ions into the sarcoplasm upon stimulation.
* **Association with dihydropyridine receptors (DHPRs):** DHPRs are voltage-sensitive receptors located in the T-tubule membrane. They act as sensors for depolarization of the muscle fiber membrane and trigger calcium release from the SR through interaction with RyRs.
* **High density of calcium ATPase pumps:** These pumps actively transport calcium ions back into the SR lumen from the sarcoplasm, ensuring relaxation of the muscle fiber.
* **Presence of specialized lipids:** The jSR membrane contains a high concentration of phospholipids, particularly phosphatidylinositol-4,5-bisphosphate (PIP2), which is involved in regulating calcium release and other signaling processes.
The jSR membrane is a highly dynamic structure that undergoes significant remodeling during muscle development and in response to various stimuli. Its intricate organization and molecular composition play a crucial role in regulating muscle contraction and force generation, highlighting its importance for muscle function.'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Ryanodine receptor 2 | A ryanodine receptor 2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q92736] | Homo sapiens (human) |
| Ryanodine receptor 1 | A ryanodine receptor 1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P21817] | Homo sapiens (human) |
Compounds (4)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| nevirapine | nevirapine : A dipyridodiazepine that is 5,11-dihydro-6H-dipyrido[3,2-b:2',3'-e][1,4]diazepine which is substituted by methyl, oxo, and cyclopropyl groups at positions 4, 6, and 11, respectively. A non-nucleoside reverse transcriptase inhibitor with activity against HIV-1, it is used in combination with other antiretrovirals for the treatment of HIV infection. Nevirapine: A potent, non-nucleoside reverse transcriptase inhibitor used in combination with nucleoside analogues for treatment of HIV INFECTIONS and AIDS. | cyclopropanes; dipyridodiazepine | antiviral drug; HIV-1 reverse transcriptase inhibitor |
| bastadin 5 | |||
| bastadin 4 | |||
| chlorantranilipole | chlorantranilipole: anthranilic diamide insecticide.that disrupts mating in codling moth (Lepidoptera: Tortricidae) chlorantraniliprole : A carboxamide resulting from the formal condensation of the carboxylic acid group of 3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxylic acid with the primary amino group of 2-amino-5-chloro-N,3-dimethylbenzamide. The first of the anthranilic diamide insecticides, it is a ryanodine receptor activator and is used to protect a wide variety of crops, including corn, cotton, grapes, rice and potatoes. | monochlorobenzenes; organobromine compound; pyrazole insecticide; pyrazoles; pyridines; secondary carboxamide | ryanodine receptor agonist |