Target type: biologicalprocess
Any process that activates or increases the frequency, rate or extent of the binding or confining calcium ions such that they are separated from other components of a biological system. [GOC:ai]
Positive regulation of sequestering of calcium ion is a crucial biological process that involves the controlled removal of calcium ions (Ca2+) from the cytosol, the fluid within a cell, and their storage in intracellular compartments. This process plays a pivotal role in maintaining cellular calcium homeostasis, which is essential for various physiological functions.
The primary mechanism for sequestering Ca2+ involves specialized organelles called the endoplasmic reticulum (ER) and the sarcoplasmic reticulum (SR) in muscle cells. These organelles contain calcium-binding proteins, particularly calreticulin and calsequestrin, which act as calcium buffers. These proteins bind to Ca2+ and store it within the ER or SR lumen.
The sequestration process is tightly regulated by a complex interplay of proteins, including:
**1. Calcium pumps:** These transmembrane proteins, such as the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump, actively transport Ca2+ from the cytosol into the ER or SR lumen against their concentration gradient. This requires energy, supplied by ATP hydrolysis.
**2. Calcium channels:** These proteins embedded in the ER or SR membrane allow the controlled release of Ca2+ from these compartments back into the cytosol. Several types of calcium channels exist, including the inositol trisphosphate receptor (IP3R) and the ryanodine receptor (RyR), which are activated by specific signaling molecules.
**3. Calcium-binding proteins:** As mentioned earlier, proteins like calreticulin and calsequestrin within the ER or SR lumen bind to Ca2+ and store it. These proteins act as calcium buffers, preventing excessive accumulation of free Ca2+ within these compartments.
**4. Calcium-dependent signaling pathways:** The concentration of Ca2+ within the cytosol acts as a signal, triggering various cellular processes. Once released from the ER or SR, Ca2+ binds to specific proteins, initiating downstream signaling pathways.
The positive regulation of sequestering of calcium ion ensures that Ca2+ levels in the cytosol remain within a narrow range. This process is essential for various cellular functions, including:
- Muscle contraction: Ca2+ released from the SR triggers the interaction between actin and myosin filaments, leading to muscle contraction.
- Neurotransmitter release: Ca2+ influx into presynaptic terminals triggers the release of neurotransmitters into the synaptic cleft, enabling communication between neurons.
- Cell signaling: Ca2+ acts as a second messenger, activating various signaling pathways involved in cell growth, differentiation, and apoptosis.
In summary, positive regulation of sequestering of calcium ion is a highly coordinated process that involves the active transport of Ca2+ into intracellular compartments, its storage by calcium-binding proteins, and the controlled release of Ca2+ back into the cytosol. This process is crucial for maintaining calcium homeostasis and regulating various cellular functions.'
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| 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) |
| Peptidyl-prolyl cis-trans isomerase FKBP1B | A peptidyl-prolyl cis-trans isomerase FKBP1B that is encoded in the genome of human. [PRO:DNx, UniProtKB:P68106] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| tacrolimus | tacrolimus (anhydrous) : A macrolide lactam containing a 23-membered lactone ring, originally isolated from the fermentation broth of a Japanese soil sample that contained the bacteria Streptomyces tsukubaensis. Tacrolimus: A macrolide isolated from the culture broth of a strain of Streptomyces tsukubaensis that has strong immunosuppressive activity in vivo and prevents the activation of T-lymphocytes in response to antigenic or mitogenic stimulation in vitro. | macrolide lactam | bacterial metabolite; immunosuppressive agent |
| cyclosporine | ramihyphin A: one of the metabolites produced by Fusarium sp. S-435; RN given refers to cpd with unknown MF | homodetic cyclic peptide | anti-asthmatic drug; anticoronaviral agent; antifungal agent; antirheumatic drug; carcinogenic agent; dermatologic drug; EC 3.1.3.16 (phosphoprotein phosphatase) inhibitor; geroprotector; immunosuppressive agent; metabolite |
| sirolimus | sirolimus : A macrolide lactam isolated from Streptomyces hygroscopicus consisting of a 29-membered ring containing 4 trans double bonds, three of which are conjugated. It is an antibiotic, immunosupressive and antineoplastic agent. Sirolimus: A macrolide compound obtained from Streptomyces hygroscopicus that acts by selectively blocking the transcriptional activation of cytokines thereby inhibiting cytokine production. It is bioactive only when bound to IMMUNOPHILINS. Sirolimus is a potent immunosuppressant and possesses both antifungal and antineoplastic properties. | antibiotic antifungal drug; cyclic acetal; cyclic ketone; ether; macrolide lactam; organic heterotricyclic compound; secondary alcohol | antibacterial drug; anticoronaviral agent; antineoplastic agent; bacterial metabolite; geroprotector; immunosuppressive agent; mTOR inhibitor |
| 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 |