![]() The binding of an antigen to its receptor on a B cell (the BCR) also generates the second messengers DAG and IP 3.Īs the functions of IP 3 and DAG indicate, calcium ions are also important intracellular messengers. The remarkable ability of tacrolimus and cyclosporine to prevent graft rejection is due to their blocking this pathway. The calcium rise is needed for NF-AT (the "nuclear factor of activated T cells") to turn on the appropriate genes in the nucleus. The rise in intracellular calcium triggers the response. inositol-1,4,5-trisphosphate ( IP 3): This soluble molecule diffuses through the cytosol and binds to receptors on the endoplasmic reticulum causing the release of calcium ions (Ca 2+) into the cytosol.These are made available by the action of the other second messenger - IP 3. As its name suggests, activation of PKC requires calcium ions. It recruits Protein Kinase C ( PKC) - a calcium-dependent kinase that phosphorylates many other proteins that bring about the changes in the cell. diacylglycerol ( DAG): DAG remains in the inner layer of the plasma membrane. ![]() Figure 4.14.3 IP3 and DAGĪs its name suggests, it hydrolyzes phospholipids - specifically phosphatidylinositol-4,5-bisphosphate (PIP 2) which is found in the inner layer of the plasma membrane. Peptide and protein hormones like vasopressin, thyroid-stimulating hormone ( TSH), and angiotensin and neurotransmitters like GABA bind to G protein-coupled receptors (GPCRs) that activate the intracellular enzyme phospholipase C ( PLC). Inositol trisphosphate (IP 3) and diacylglycerol (DAG) ![]()
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