Chapter 15 (Post Midterm 1)
Chapter 15 (Post Midterm 1) MOLGEN 5607 - 0010
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This 2 page Class Notes was uploaded by Sampath Choppara on Tuesday October 6, 2015. The Class Notes belongs to MOLGEN 5607 - 0010 at Ohio State University taught by Iris Meier,Paul Herman in Fall 2015. Since its upload, it has received 89 views. For similar materials see Cell Biology in Biochemistry at Ohio State University.
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Date Created: 10/06/15
Chapter 15 Cell Signaling Post Midterm 1 Friday October 2 2015 152 PM SIGNALING THROUGH GPROTEIN COUPLED RECEPTORS I Gprotein coupled receptors GPCRlargest family of cellsurface mediators a Mediate more responses from the external world and other cells to signals b Diverse chemically and functionally but not structurally Multipass transmembrane protein made of one polypeptide chain Ligand binding site present in the center c Inactive GPCR bound to trimeric Gprotein i 3 subunits a B and 7 ii Associated with the membrane but NOT integral They only have a lipid group attached to the membrane d Extracellular signal binds to GPCR and the receptor undergoes conformational change i New conformation change allows GPCR to bind to Gprotein and activate it At its inactive conformation G protein is bound to GDP Extracellular signal ligand binding to GPCR causes a conformation change 0 GProtein via its a subunit can now bind to GPCR Binding to GPCR causes a conformation change in 0 subunit and releases GPE 0 So GPCR is really acting like a giant exchange factor 0 0t subunit binds to GTP and is NOW active 0 Activation of a subunit causes dissociation of the B and 7 subunits All subunits are now active and go on to interact with targets to relay signals ii a subunit remains active until GTP is hydrolyzed to GDP 1 GTP Hydrolysis is aided by Regulator of GProtein signaling RGS Studysoup notes Page 1 H G Proteins and the production of cyclic AMP CAMP a Receptor activation usually leads to production of messengers inside the cell that help propogate the signal further b CAMP second messenger in some signaling pathways i Synthesized by adenylyl cyclase ii Rapidlycontinuously destroyed by CAMP phosphodiesters Extracellular signals via ligand binding activate GPCR which activates a stimulatory G protein x subunit pictured 0 a subunit binds to and activates adenylyl cyclase which converts ATP to cylic AMP 0 CAMP inside cell increases rapidly CAMP activates CAMP dependent protein kinase PKA Inactive state 2 regulatory subunits and 2 catalytic subunits Made active when CAMP binds to regulatory subunit and conformation Change causes it to dissociate from catalytic subunits Catalytic subunits of PKA now active capable of phosphorylating specific target proteins I Ill Inactive Protein Kinase I I Regulatory subunits Catalytic subunits ACt39VatEd PKA 39 Activated PKA PKA can cross nuclear membrane via pore to 39 phosphorylate target proteins Nuclear pore Negative Feedback PKA phosphorylates phosphodiesterase which lowers CAMP 0 CRE Binding Protein CREB also phosphorylated o CREB transcription regulator of gene that encodes hormone somatostatin CREB recruits coaCtivator CREB Binding Protein to stimulate transcription of target genes Phosphodiesterase I S Activated target gene CREBinding ProteinCREB Coactivator CREBBindin protein CBP TKHNSCKIPTID 939 Studysoup notes Page 2
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