Enzyme Linked Membrane Receptors Extracellular ligand binding domain Intracellular catalytic domain Mostcommon catalytic domains have tyrosine kinase activity Adds a phosphate group to itself auto phosphorylation conformational change allowing binding catalytic phosphorylation of specific targetproteins Adds aphosphate group to a tyrosine in specific targetproteins Some catalytic domains have guanyly cyclase activity r ConvertGTP to cGMP asecondary messenger Receptor Tyrosine Kinases Insulin interacts with cellula receptor tyrosine kinase Peptide hormone thatis produced by B cells of Islets of Langerhans in pancreas Ligand binding domain acIds a n N Mr achain s rgs meansarenainme Insulin Signaling Cascade Ligand Binding I Da scan nounasaagnaasanashere Inside a outside Erase anin anin anin registrich Insulin binds to extracellular domains of receptor activates catalytic domain inside cell Catalytic domain in one receptor phosphorylates Tyr residues in another receptor Receptor autophosphorylation allows binding and phosphorylation of protein IRS 1 IndirectInteraction of phosphorylated IRS with protein Bas Initiates a series of protein phosphorylations ERK I phosphorylated protein kinases enters nucleus Transcription factor E1K1 becomes phosphorylated Stimulates expression of specific genes e g glucose transporter GLUT4C Reaches targetcells liver muscle or fat cells via bloodstream Binding to receptor initiates a cascade of events leads to increased glucose uptake and metabolism Inability to make sense Insulin Diabetes Insulin Receptor Glucose Importin Myocytes 2 When insulin interacts with its receptor vesicles more to the surface and fuse with the plasma membrane Increasing the number of glucose transporters In the plasma membrane 3 when insulin level drops glucose transporters are removed from the plasma membrane byendocytosis forming small vesicles asGlucose areinnerinasas4 The smaller resides fuse with a larger endosome Insulin levels rise again
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