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In biochemistry, a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the high-energy ATP molecule donates a phosphate group to the substrate molecule. This transesterification produces a phosphorylated substrate and ADP. Conversely, it is referred to as dephosphorylation when the phosphorylated substrate donates a phosphate group and ADP gains a phosphate group. These two processes, phosphorylation and dephosphorylation, occur four times during glycolysis.
Sphingolipids are a class of lipids containing a backbone of sphingoid bases, which are a set of aliphatic amino alcohols that includes sphingosine. They were discovered in brain extracts in the 1870s and were named after the mythological sphinx because of their enigmatic nature. These compounds play important roles in signal transduction and cell recognition. Sphingolipidoses, or disorders of sphingolipid metabolism, have particular impact on neural tissue. A sphingolipid with a terminal hydroxyl group is a ceramide. Other common groups bonded to the terminal oxygen atom include phosphocholine, yielding a sphingomyelin, and various sugar monomers or dimers, yielding cerebrosides and globosides, respectively. Cerebrosides and globosides are collectively known as glycosphingolipids.
Ceramides are a family of waxy lipid molecules. A ceramide is composed of sphingosine and a fatty acid joined by an amide bond. Ceramides are found in high concentrations within the cell membrane of eukaryotic cells, since they are component lipids that make up sphingomyelin, one of the major lipids in the lipid bilayer. Contrary to previous assumptions that ceramides and other sphingolipids found in cell membrane were purely supporting structural elements, ceramide can participate in a variety of cellular signaling: examples include regulating differentiation, proliferation, and programmed cell death (PCD) of cells.
Sphingosine kinase (SphK) is a conserved lipid kinase that catalyzes formation sphingosine-1-phosphate (S1P) from the precursor sphingolipid sphingosine. Sphingolipid metabolites, such as ceramide, sphingosine and sphingosine-1-phosphate, are lipid second messengers involved in diverse cellular processes. There are two forms of SphK, SphK1 and SphK2. SphK1 is found in the cytosol of eukaryotic cells, and migrates to the plasma membrane upon activation. SphK2 is localized to the nucleus.
Lipid signaling, broadly defined, refers to any biological signaling event involving a lipid messenger that binds a protein target, such as a receptor, kinase or phosphatase, which in turn mediate the effects of these lipids on specific cellular responses. Lipid signaling is thought to be qualitatively different from other classical signaling paradigms because lipids can freely diffuse through membranes. One consequence of this is that lipid messengers cannot be stored in vesicles prior to release and so are often biosynthesized "on demand" at their intended site of action. As such, many lipid signaling molecules cannot circulate freely in solution but, rather, exist bound to special carrier proteins in serum.
Sphingosine-1-phosphate (S1P) is a signaling sphingolipid, also known as lysosphingolipid. It is also referred to as a bioactive lipid mediator. Sphingolipids at large form a class of lipids characterized by a particular aliphatic aminoalcohol, which is sphingosine.
Sphingosine-1-phosphate receptor 1, also known as endothelial differentiation gene 1 (EDG1) is a protein that in humans is encoded by the S1PR1 gene. S1PR1 is a G-protein-coupled receptor which binds the bioactive signaling molecule sphingosine 1-phosphate (S1P). S1PR1 belongs to a sphingosine-1-phosphate receptor subfamily comprising five members (S1PR1-5). S1PR1 was originally identified as an abundant transcript in endothelial cells and it has an important role in regulating endothelial cell cytoskeletal structure, migration, capillary-like network formation and vascular maturation. In addition, S1PR1 signaling is important in the regulation of lymphocyte maturation, migration and trafficking.
Sphingosine-1-phosphate receptor 3 also known as S1PR3 is a human gene which encodes a G protein-coupled receptor which binds the lipid signaling molecule sphingosine 1-phosphate (S1P). Hence this receptor is also known as S1P3.
Sphingosine-1-phosphate receptor 2, also known as S1PR2 or S1P2, is a human gene which encodes a G protein-coupled receptor which binds the lipid signaling molecule sphingosine 1-phosphate (S1P).
In enzymology, a glycosphingolipid deacylase is an enzyme that catalyzes a chemical reaction that cleaves gangliosides and neutral glycosphingolipids, releasing fatty acids to form the lyso-derivatives.
In enzymology, a ceramide kinase, also abbreviated as CERK, is an enzyme that catalyzes the chemical reaction:
The ASAH1 gene encodes in humans the acid ceramidase enzyme.
Neutral ceramidase is an enzyme that in humans is encoded by the ASAH2 gene.
Neutral ceramidase C also known as N-acylsphingosine amidohydrolase 2C or non-lysosomal ceramidase C or ASAH2C is a ceramidase enzyme which in humans is encoded by the ASAH2C gene.
Alkaline ceramidase 1 also known as ACER1 is a ceramidase enzyme which in humans is encoded by the ACER1 gene.
Alkaline ceramidase 2 also known as ACER2 is a ceramidase enzyme which in humans is encoded by the ACER2 gene.
Safingol is a lyso-sphingolipid protein kinase inhibitor. It has the molecular formula C18H39NO2 and is a colorless solid. Medicinally, safingol has demonstrated promising anticancer potential as a modulator of multi-drug resistance and as an inducer of necrosis. The administration of safingol alone has not been shown to exert a significant effect on tumor cell growth. However, preclinical and clinical studies have shown that combining safingol with conventional chemotherapy agents such as fenretinide, vinblastine, irinotecan and mitomycin C can dramatically potentiate their antitumor effects. Currently in Phase I clinical trials, it is believed to be safe to co-administer with cisplatin.
Sphingosine kinase 2 is a protein that in humans is encoded by the SPHK2 gene.
Functional inhibitors of acid sphingomyelinase, or FIASMA, is a large group of pharmacological compounds inhibiting the enzyme acid sphingomyelinase. This enzyme is mainly located within the lysosome, where it cleaves sphingomyelin to ceramide and sphingosine, the latter of which is then phosphorylated to sphingosine-1-phosphate. These metabolites, and subsequent inhibition of the enzyme, influence the balance between cell death (apoptosis) and cell growth (proliferation). A lack of regulation of this sensitive equilibrium can lead to serious clinical consequences.
Sphingomyelin deacylase (EC 3.5.1.109, SM deacylase, GcSM deacylase, glucosylceramide sphingomyelin deacylase, sphingomyelin glucosylceramide deacylase, SM glucosylceramide GCer deacylase, SM-GCer deacylase, SMGCer deacylase) is an enzyme with systematic name N-acyl-sphingosylphosphorylcholine amidohydrolase. This enzyme catalyses the following chemical reaction
References
- 1 2 Mao C, Obeid LM (September 2008). "Ceramidases: regulators of cellular responses mediated by ceramide, sphingosine, and sphingosine-1-phosphate". Biochim. Biophys. Acta. 1781 (9): 424–34. doi:10.1016/j.bbalip.2008.06.002. PMC 2614331 . PMID 18619555.
- ↑ Otsuka Y, Airola M, Choi Y, Coant N, Snider J, Cariello C, Saied E, Arenz C, Bannister T, Rahaim R, Hannun Y, Shumate J, Scampavia L, Haley J, Spicer TP (2020). "Identification of Small-Molecule Inhibitors of Neutral Ceramidase (nCDase) via Target-Based High-Throughput Screening". SLAS Discovery. doi:10.1177/2472555220945283. PMC 7749003 . PMID 32734807.
