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An example of upregulation is the response of liver cells exposed to such xenobiotic molecules as dioxin. In this situation, the cells increase their production of cytochrome P450 enzymes, which in turn increases degradation of these dioxin molecules. Downregulation or upregulation of an RNA or protein may also arise by an epigenetic alteration ...
An example of a coupled reaction is the phosphorylation of fructose-6-phosphate to form the intermediate fructose-1,6-bisphosphate by the enzyme phosphofructokinase accompanied by the hydrolysis of ATP in the pathway of glycolysis. The resulting chemical reaction within the metabolic pathway is highly thermodynamically favorable and, as a ...
It is widely used for the specific uptake of certain substances required by the cell (examples include LDL via the LDL receptor or iron via transferrin). The role of receptor-mediated endocytosis is well recognized to up take downregulation of transmembrane signal transduction but can also promote sustained signal transduction. [3]
Immune dysregulation is any proposed or confirmed breakdown or maladaptive change in molecular control of immune system processes. For example, dysregulation is a component in the pathogenesis of autoimmune diseases and some cancers.
Downregulation of protein kinase A occurs by a feedback mechanism and uses a number of cAMP hydrolyzing phosphodiesterase (PDE) enzymes, which belong to the substrates activated by PKA. Phosphodiesterase quickly converts cAMP to AMP, thus reducing the amount of cAMP that can activate protein kinase A. PKA is also regulated by a complex series ...
Basic mechanism used by viral vectors to deliver genes to target cells. Example shown is a lentiviral vector. There are several challenges associated with gene silencing therapies, including delivery and specificity for targeted cells. For instance, for treatment of neurodegenerative disorders, molecules for a prospective gene silencing therapy ...
Food chain in a Swedish lake. Osprey feed on northern pike, which in turn feed on perch which eat bleak which eat crustaceans.. A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as earthworms and woodlice ...
MHC class I molecules are heterodimers that consist of two polypeptide chains, α and β 2-microglobulin (B2M). The two chains are linked noncovalently via interaction of B2M and the α 3 domain. Only the α chain is polymorphic and encoded by a HLA gene, while the B2M subunit is not polymorphic and encoded by the beta-2 microglobulin gene.