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.
Sphingomyelin is a type of sphingolipid found in animal cell membranes, especially in the membranous myelin sheath that surrounds some nerve cell axons. It usually consists of phosphocholine and ceramide, or a phosphoethanolamine head group; therefore, sphingomyelins can also be classified as sphingophospholipids. In humans, SPH represents ~85% of all sphingolipids, and typically make up 10–20 mol % of plasma membrane lipids.
Fumonisin B1 is the most prevalent member of a family of toxins, known as fumonisins, produced by several species of Fusarium molds, such as Fusarium verticillioides, which occur mainly in maize (corn), wheat and other cereals. Fumonisin B1 contamination of maize has been reported worldwide at mg/kg levels. Human exposure occurs at levels of micrograms to milligrams per day and is greatest in regions where maize products are the dietary staple.
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.
Fatty-acyl-CoA Synthase, or more commonly known as yeast fatty acid synthase, is an enzyme complex responsible for fatty acid biosynthesis, and is of Type I Fatty Acid Synthesis (FAS). Yeast fatty acid synthase plays a pivotal role in fatty acid synthesis. It is a 2.6 MDa barrel shaped complex and is composed of two, unique multi-functional subunits: alpha and beta. Together, the alpha and beta units are arranged in an α6β6 structure. The catalytic activities of this enzyme complex involves a coordination system of enzymatic reactions between the alpha and beta subunits. The enzyme complex therefore consists of six functional centers for fatty acid synthesis.
In enzymology, a long-chain-alcohol O-fatty-acyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a serine C-palmitoyltransferase (EC 2.3.1.50) is an enzyme that catalyzes the chemical reaction:
Sterol O-acyltransferase is an intracellular protein located in the endoplasmic reticulum that forms cholesteryl esters from cholesterol.
In enzymology, a ceramide kinase, also abbreviated as CERK, is an enzyme that catalyzes the chemical reaction:
Serine palmitoyltransferase, long chain base subunit 2, also known as SPTLC2, is a protein which in humans is encoded by the SPTLC2 gene. SPTLC2 belongs to the class-II pyridoxal-phosphate-dependent aminotransferase family.
Acyl-coenzyme A thioesterase 11 also known as StAR-related lipid transfer protein 14 (STARD14) is an enzyme that in humans is encoded by the ACOT11 gene. This gene encodes a protein with acyl-CoA thioesterase activity towards medium (C12) and long-chain (C18) fatty acyl-CoA substrates which relies on its StAR-related lipid transfer domain. Expression of a similar murine protein in brown adipose tissue is induced by cold exposure and repressed by warmth. Expression of the mouse protein has been associated with obesity, with higher expression found in obesity-resistant mice compared with obesity-prone mice. Alternative splicing results in two transcript variants encoding different isoforms.
Very-long-chain 3-oxoacyl-CoA synthase (EC 2.3.1.199, very-long-chain 3-ketoacyl-CoA synthase, very-long-chain beta-ketoacyl-CoA synthase, condensing enzyme, CUT1 (gene), CERS6 (gene), FAE1 (gene), KCS (gene), ELO (gene)) is an enzyme with systematic name malonyl-CoA:very-long-chain acyl-CoA malonyltransferase (decarboxylating and thioester-hydrolysing). This enzyme catalyses the following chemical reaction
Ceramide synthase 1 also known as LAG1 longevity assurance homolog 1 is an enzyme that in humans is encoded by the CERS1 gene.
Ceramide synthase 2, also known as LAG1 longevity assurance homolog 2 or Tumor metastasis-suppressor gene 1 protein is an enzyme that in humans is encoded by the CERS2 gene.
Ceramide synthase 3 (CersS3), also known as longevity assurance homologue 3, is an enzyme that is encoded in humans by the CERS3 gene.
Ceramide synthase 4 (CerS4) is an enzyme that in humans is encoded by the CERS4 gene and is one of the least studied of the ceramide synthases.
Ceramide synthase 5 (CerS5) is the enzyme encoded in humans by the CERS5 gene.
Acyl-CoA thioesterase 1 is a protein that in humans is encoded by the ACOT1 gene.
