Biol 2056 2024 L2+3 Past Paper PDF

Biol 2056 signalling cascades Biol 2056. Nullin divecha, ([email protected]) ure 2 2024 L2+3 1. Each cell type has a unique repertoire of cell signalling components (signalsome). 2. During differentiation cells express a par...

Biol 2056 signalling cascades Biol 2056. Nullin divecha, ([email protected]) ure 2 2024 L2+3 1. Each cell type has a unique repertoire of cell signalling components (signalsome). 2. During differentiation cells express a particular phenotype and a distinctive set of signalling components (a cell-type-specific signalsome) required to control their particular functions. 3. Abnormal remodelling of cellular signalsomes creates signalling defects that have great significance for the onset of many diseases. http://www.cellsignallingbiology.org/csb/  Biol 2056 Reading list and Possible exam questions 2024 L2+3 Reading list: 1. Expansion of signal transduction by G proteins The second 15 years or so: From 3 to 16 α subunits plus βγ dimers 2. Cell Signaling by Receptor Tyrosine Kinases 1. Describe in detail how b adrenergic agonists can induce an increase in myocardial contraction 2. Explain how b adrenergic agonist induce two different responses in different tissues. 3. Compare and contrast alpha and beta adrenergic receptor signalling pathways. 4. Illustrate how protein phosphorylation modulates downstream signalling Adrenergic activation induces a variety of responses in different Biol 2056 tissues during the flight or fight response : How? 2024 L2+3 Fight or Flight Adrenaline Noradrenaline (epinephrine) Decrease Liberati Decreas d on of ed peripher Increase Increase energy Increase Increase stomach al blood d d supply d blood d flow and cardiac oxygen flow to muscle (fat and intestina Vasoconstricti output supply muscles tension on glycoge l Skin, n) motility Kidney GIT Increase strength and heart rate Increased blood flow to muscle Increased systemic and cellular energy supply Increased skeletal muscle force  Adrenergic system Biol 2056 2024 L2+3 hetic nervous system Post ganglionic fibres release norepinephrine at the target Norepinephrine enal medulla (post ganglionic tissue) releases adrenalin into the blood stream (en Epinephrine (adrenalin) norephinephrine Into the blood stream  Adrenergic agonist derived responses can be split according to the Biol 2056 activation of at least two different receptor dependent pathways. 2024 L2+3 Adrenergic stimulation Alpha adrenoreceptors Beta-adrenoreceptors smoot Skelet h Adipos Cardia Liver al muscle e c cells Glycogen muscle cells breakdown Lipolysis Increased Increased contraction contraction Contraction andIncreased heart rate glucose Free fatty acids Increased Vasoconstriction Increased force Excitation/ Ahlquist R.P. A Study of the Adenotrophic Receptors, Am. J. Contraction Physiol. 1948 153:586-600: “The adrenotropic receptors are coupling those hypothetical structures or systems located in, on or near the muscle or gland cells affected by epinephrine”  Biol 2056 A typical signal transduction pathway 2024 L2+3 e.g., hormone extracellular ligand- binding domain Receptor outside inside intracellular signal- hormone, cytokine, transducing domain Adaptor growth factor receptor Intracellular signal plasma generator cytoplasm (‘2nd messengers’) Protein cellular cellular kinase(s) functions functions Substrate proteins P transcription Biological effects nucleus  Biol 2056 nalin activates the phosphorylase enzyme to induce glycogen breakdown 2024 L2+3 The Corys had Flight fright adrenalin defined that there response were two forms of phosphorylase in liver and had postulated that homogenise something converted one to the Liver Assay other Glycogen phosphorylase breakdown Krebs and Fisher Glycogen characterised a Glucose-1P converting enzyme breakdown and later showed that the converting enzyme phosphorylated glucose phosphorylase The enzyme is called phosphorylase as it uses phosphate to attack the But what is between glycogen bond (hyro-lase: glucose adrenalin and uses water)  Biol 2056 Sometimes you just have to get your hands dirty: 2024 L2+3 Soluble fraction homogenise lysate pelletsoluble ` centrifuge adrenalin adrenalin adrenalin X phosphorylase phosphorylase 1. Adrenalin stimulates something in the membrane pellet 2. This generates a water soluble product that leads to phosphorylase activatio  cAMP is the critical adrenaline induced second messenger that Biol 2056 leads to the activation of phosphorylase 2024 L2+3 + Adenylate c-AMP phosphodiesterase cyclase Forskolin indian coleus plant) ATP AMP cAMP Analogues Di-butyryl-cAMP phosphorylase Adenylate cyclase is activated in response to adrenaline Biol 2056 stimulation to generate cAMP 2024 L2+3 Six classes of adenylate cyclases and the class III are the major ones in mammalian cells. The enzymes are membrane bound. The N terminus, c1 and c2 regions appear to be important for regulation by Ga-GTP Complex signalling in mammalian cells There are 10 isoforms of adenylate cyclase in mammalian cells: Isoforms III, V and VIII are stimulated by Ga subunits and can be stimulated by the Ca2+/calmodulin, while Isoforms I and VI are inhibited by Ca2+. Suggests cross talk between different signalling pathways From the Sutherland Nobel lecture “we still do not understand how the hormone-receptor interaction Medicine, 1994: Alfred Gilman and Martin Rodbell: "for their Biol 2056 discovery of G-proteins and their role in signal transduction in 2024 L2+3 cells" Serendipity: the mother of discovery. (but only when you are really really sm Ligand bound GPCR Acts as a GEF g b Ga Adenylate Ga (GDP ) g (GTP) cyclase b Heterotrimeric G-protein Dissociation cAMP Not essential: THE INFANCY OF SIGNAL TRANSDUCTION—GTP STIMULATION OF cAMP Heterotrimeric G-protein activation cycle. Biol 2056 2024 L2+3 1. GPCR interact with their cognate ligand which induces a conformational change in the receptor 2. GPCR-ligand stimulates the exchange of GDP to GTP on the Ga subunit 3. GTP exchanges stimulates the dissociation of Ga from the bg subunits (note they all remain at the membrane through lipid modification that inserts into the membrane). 4. Ga subunit stimulates an effector (adenylate cyclase) 5. Intrinsic or stimulated GTPase activity of Ga returns the subunit to resting state and association with bg n Kinase A is a critical downstream target for cAMP Biol 2056 er and Edwin G. Krebs in 1968. They won the Nobel Prize in Physiology or Medicine in 1992 2024 L2+3 Protein kinase A occurs in an inactive form (R2C2), consisting of two regulatory (inhibitory) subunits and two catalytic subunits, and in an active form (2C). cAMP activates protein kinase A by dissociation of the R-subunits from the R2C2-complex (allosteric activation). cAMP induces conformational change P P substrate substrate The R-subunits contain a pseudosubstrate sequence: Arg - Arg - Gly - Ala - Ile, which binds to the catalytic site of the C-subunits. Binding of cAMP allosterically moves the pseudosubstrate sequence out of the catalytic sites. Protein kinase A modulates the activity of many proteins by phosphorylating them. Phosphorylase kinase is a direct target for cAMP dependent PKA Biol 2056 and couples receptor activation with increased glycogenolysis 2024 L2+3 Ligand bound GPCR Flight fright Acts as a GEF response g b Ga (GDP) g Ga (GTP) Adenylate cyclase Membrane bound b Heterotrimeric G-protein Dissociation Liver cAMPSoluble second messenger Glycogen breakdown PKAin PKAAC Activated PKA Inactive Active P Phosphorylase Phosphorylase glucose kinaseb kinasea Inactive Active P Phosphorylaseb Phosphorylasea glycogenolysis Regulation of phosphorylase Biol 2056 2024 L2+3 Yellow: AMP allosteric site Orange: ser14 phosphorylation site Blue: glycogen binding site Red: catalytic site Ser14 is close to the subunit interface. The structural change associated with phosphorylation, and with the conversion of phosphorylase b to phosphorylase a, is the rearrangement of the originally disordered residues 10 to 22 into α helices (tower helices). This change increases phosphorylase activity. In muscle AMP is a potent activator of phosphorylase in the absence of phosphorylation In liver however enzyme completely inactive unless  Phosphorylation of phosphorylase induces a conformation Biol 2056 change in the active site 2024 L2+3 Active site Phosphorylation at Serine14 Conformational change occurs quite far from the phosphorylation site Phosphorylation causes long range structural changes Phosphorylaseb (inactive) Phosphorylasea (active) Shown is the phosphorylase dimer. Phosphorylase is activated by a change of shape. The shift between the two shapes is controlled by phosphorylation of serine 14 (coloured pink). Note the change in shape around the active site (left-hand side of the upper subunit). cAMP activation of PKA and phosphorylation of different Biol 2056 targets coordinates a cellular response to increase glucose 2024 L2+3 synthesis and release. cAMP PKAin PKAAC Flight fright response P Pyruvate Phosphorylase Glycogen synthase Kinase(AC) Liver kinasea Glycogen P breakdown P P Pyruvate Phosphorylasea Glycogen synthase Kinase (inac) Increased glycogen Block glycogen Block glucose breakdown synthesis glycolysis Increase gluconeogen esis  Biol 2056 A typical signal transduction pathway 2024 L2+3 e.g., hormone extracellular ligand- binding domain Receptor outside inside intracellular signal- hormone, cytokine, transducing domain Adaptor growth factor receptor way to switch Intracellular off receptor signal plasma generator way to switch cytoplasm off signal (‘2nd messengers’) Protein cellular cellular kinase(s) functions functions Substrate proteins P transcription way to reverse Biological effects nucleus the effect (phosphatase) Switching off GPCR and cAMP signalling Biol 2056 2024 L2+3 Ligand bound GPCR Acts as a GEF Ga Adenylate (GTP) cyclase cAMP Receptor Ga inactivation cAMP inactivation desensitisation GPCR c-terminal tail Intrinsic or GAP stimulated Activation of phosphorylation GTPase activity (RGS proteins) phosphodiesterase b-adrenergic receptor kinase activity (PDE) Phosphorylated tails GTP hydrolysis which: Hydrolysis of recruit b-arrestin, which: 1. Stops activation of cAMP to 1. Attenuates downstream targets generate AMP heterotrimeric G 2. Causes re-association protein activation of the Ga subunit with 2. Induces receptor the bg subunits internalisation How does b-adrenergic signalling stimulate the release of Free Biol 2056 Fatty acids into the blood stream? 2024 L2+3 Ligand bound GPCR Acts as a GEF g b Ga Ga Adenylate Membrane bound cyclase Adipos (GDP) (GTP) g b Heterotrimeric G-protein Dissociation e cAMPSoluble second messenger Lipolysis PKAin PKAAC s659 s660 P P PKA phosphorylates; P Hormone sensitive Free fatty acids 1. HSL , leads to Lipase (HSL) perilipin translocation to the lipid droplet and its Lipid TAG activation dropl 2. Perilipin acts as a barrier to lipid et DAG hydrolysis. Phosphorylation TAG=triacylglycerol DAG=Diacylglycerol How does b-adrenergic signalling stimulate increased heart rate Biol 2056 and force? 2024 L2+3 Adrenergic stimulation Depolarisation Sinoatrial node Ligand bound GPCR Ca2+ Acts as a GEF PCa v1.2 contraction g Ca2+ Ca2+ b + Ga Ga Adenylate (GDP) g (GTP) cyclase b Heterotrimeric G-protein Dissociation PKA RYR cAMP AKA P P cAMP AKA PKA P Ca2+ P - P L T tubule serc Sarcoplasmic a Reticulum (SR) Localised activated PKA phosphorylates 1. The Cav1.2 ion channel which increases Ca2+ influx in response to depolarisation 2. The ryanodine receptor (RYR) stimulates increased calcium induced calcium release from SR 3. Phospholambam and prevents it from inhibiting SERCA mediated Ca2+ uptake. Enable faster relaxation for next contraction  Cell specific targets of PKA define specific outputs in response to b- Biol 2056 adrenergic receptor stimulation 2024 L2+3 Adrenergic stimulation b1 b2 b3 b2 Skelet Cardia Adipos Liver al c cells e muscle cAMP PKA Activated PKA P P P P P Phosphorylase P P Phosphorylase P L kinasea P Hormone sensitive kinasea P P perilipin Lipase (HSL) Phosphorylasea Ca v1.2 RYRphospholambam P Phosphorylasea RYR2 Increased heart rate Increased Increased force glucose Free fatty acids Excitation/ Contraction  Biol 2056 signalling cascades Biol 2056. Nullin divecha, ([email protected]) ure 3 2024 L2+3 1. Each cell type has a unique repertoire of cell signalling components (signalsome). 2. During differentiation cells express a particular phenotype and a distinctive set of signalling components (a cell-type-specific signalsome) required to control their particular functions. 3. Abnormal remodelling of cellular signalsomes creates signalling defects that have  Adrenergic agonist derived responses can be split according to the Biol 2056 activation of at least two different receptor dependent pathways. 2024 L2+3 Adrenergic stimulation (in vivo and in vitro assays) Alpha adrenoreceptors Beta-adrenoreceptors smoot Skelet h Adipos Cardia Liver al muscle e c cells Glycogen muscle cells breakdown Lipolysis Increased Increased contraction contraction Contraction andIncreased heart rate glucose Free fatty acids Increased Vasoconstriction Increased force Excitation/ Contraction coupling uist R.P. A Study of the Adenotrophic Receptors, Am. J. Physiol. 1948 153:586-600 GPCR including the a2-adrenoreceptor can also couple to G Biol 2056 proteins that inhibit cAMP synthesis. 2024 L2+3 PL cAMP cAMP C SMG RHO  Biol 2056 terial toxins can differentiate between different types of G-protein signalling. 2024 L2+3 Cholera toxin Switches on Gs (vibrio cholerae) as Adenylate Enterocytes as b  cyclase Cl- release ADP ribosylates H2O active ATP cAMP Pertussis toxin Switches off Gi (Whooping cough) Adenylate cyclase ai ai b  b  ATP cAMP ADP ribosylates active conformation locks the bg together with a  Biol 2056 a2-receptors couple to a pertussis toxin sensitve G1/Go to inhibit 2024 L2+3 cAMP synthesis b-adrenergic a2-adrenergic Ligand bound GPCR Pertussis toxin Acts as a GEF Blocks dissociation of a and bg g g subunits b b Inhibitor Gas Ga Adenylate Gai Gai + - (GDP) g (GTP) cyclase (GTP) g (GDP) b b Dissociation Dissociation cAMP Enables modulatory control within cells by the same agonist binding to different receptors (e.g regulation of lipolysis) or cross talk between different agonist (one that stimulates Gas and another that stimulates Gai). bg subunits released from Gi/o activation also induce specific signalling pathways. Gas and Gai activation can coordinate downstream responses Biol 2056 though modulating cAMP synthesis and other pathways 2024 L2+3 b2-adrenergic stimulation induces glycogenolysis in the liver and a2 in the beta-cells of the pancreus attenuate glucose induced insulin secretion (genetic variants assocaitated with T2D). Adrenline acts on both the b3 and a2 receptor in adipose to to control adenylate cyclase and cAMP synthesis and lipolysis.  Biol 2056 a2 receptor signalling through bg subunits: inhibition by pertussis toxin 2024 L2+3 Hyperpolarization is a change in a GIRK cell's membrane potential that makes (GPCR coupled it more negative. It is the opposite of inwardly rectifying K a depolarization. It inhibits action channel) potentials by increasing the stimulus required to move the membrane potential to the action potential threshold. PI3 Hyperpolarization is often caused by PLC efflux of K+ (a cation) through K+ K K+ Alpha2channels, or GIRK influx signalling: of Cl– (an anion) + + g mediated through Cl– channels. b + Physiological 1. Autaptic (release of neurotransmitter at a synapse autoregulates its own release).Dopamine and epiniphrine release 2. Neuron to neuron inhibition 3. Pain perception : inhibition of nociception Analgesia. Many pharmacological agents that are used in pain relieve target the activation of Gi/Go GPCR. E.g opioid, serotonin, dopamine. a1-adrenoreceptor couples to Gaq and the activation of Biol 2056 phospholipase C to regulate downstream smooth muscle cell 2024 L2+3 contraction. a1 adrenoreceptors smoot h muscle cells Increased contraction Contraction and Vasoconstriction cAMP cAMP SMG RHO PLC  Phosphoinositides Biol 2056 Structure of phosphatidylinositol(4,5)bisphosphate 2024 L2+3 (PtdIns(4,5)P2) Favoured chair structure has 5 equatorial OH and 1 axial oh. Consider a turtle with its head as the axial OH then the glycerol is connected to the right flipper which is position 1. 1. Phosphatidylinositol is the parent lipid 2. Phosphorylation can occur on fatty acid chains hydrophobic the 3, 4, and the 5 position to generate seven different phosphoinositides. PLC O O 3. The phosphorylation is O O phosphodiester linkage controlled by an array of lipid HO P inositol kinases and phosphatases hydrophillic 1 6 2 4 OH (about 80 in the human OH OH HO 3P P group 5 genome) 5 5 3 4 Cytoplasm PtdIns sphoinositides as signal transducing messengers Biol 2056 2024 L2+3 1. Cannonical PLC singalling Ligands receptors Phosphoinositide PLC pathway DAG Calcium Diverse cellular outputs  GPCR (acetylcholine (muscarinic) or a1-adrenergic) act as a GEF Biol 2056 for Gaq which leads the activation of a phospholipase C and 2024 L2+3 PtdIns(4,5)P2 hydrolysis E.g a1- adrenorecepor Or acetylcholine Ligand bound GPCR (muscarinic) Acts as a GEF smoot h muscle b g cells Increased contraction Gaq Phospholipas Gaq (GDP eC g (GTP) ) b (PLC) Contraction and Vasoconstriction Heterotrimeric G-protein Dissociation PtdIns(4,5)P2 hydrolysis The phospholipase C (PLC) family Biol 2056 2024 L2+3 Core enzyme composed of the PH domain, four tandem EF domains, a split TIM barrel (X Y) and a C2 domain. The active site is in the TIM, which is interupted by an auto-inhibitory loop insert. The PH domain can interact with phosphoinositides, rac, bg. Brings the enzyme to the membrane where it is active The C2 domain interacts with calcium and with the membrane surface and contributes to Gaq binding (b –isoforms).  Biol 2056 c PLC isoforms couple receptors and stimuli to PtdIns(4,5)P2 hydrolysis 2024 L2+3 GPCR RTK Fertilisation Gai/o Gaq Pertussis toxin sensitive Ga q b g P SH 2 PLCb1 PLCb3 P PLCg1 PLCz PLC is activated in response to the activation of many different stimuli 1. Tyrosine kinase receptors (PDGF) 2. G Protein coupled receptors (Histamine) 3. Specificity of signalling is driven by specific interaction domains :for example A. PLCb1 activated by Gaq, PLCb isoforms also activated by bg signalling (Gi/o) B. Tyrosine phosphorylated receptor interacts with SH2 domain of PLCg1. PLCg1 is then tyrosine phosphorylated and activated C. During fertilisaiton sperm specific PLCz injected into the egg. Drives GPCR activate PLC mediated hydrolysis of PtdIns(4,5)P2 to Biol 2056 generate two new second messengers Diacylglycerol (DAG) and 2024 L2+3 Ins(1,4,5)P3 (DAG) Figure 15-39 Molecular Biology of the Cell (© Garland Science 2008)  Biol 2056 (1,4,5)P3 and the Ins(1,4,5)P3-Receptor 2024 L2+3 Ins(1,4,5)P3 is a water-soluble molecule and diffuses across the cytoplasm to the IP3 receptor which is found on the membrane of the endoplasmic reticulum Ins(1,4,5)P3-receptor is a ligand-gated ion channel which allows the influx of calcium cations upon activation Three isoforms of the receptor exist The receptor is made of a tetramer The receptor has the following domains: - N-terminal Ins(1,4,5)P3binding domain - Coupling domain - Transmembrane domain - Gatekeeper domain Ins(1,4,5)P3-Receptor Biol 2056 2024 L2+3 Activation of the receptor: IP3 binds to binding domain (cytosolic face) Conformational changes in other domains Channel is opened Influx of calcium into the cell from internal stores (in the ER orTheSR) signal for IP3 binding is transferred through both the N-terminal and internal coupling domains to the gatekeeper domain, which triggers a conformational change in the activation gate formed within the transmembrane/channel-forming domain. Katsuhiko Mikoshiba (2007) IP3 receptor/Ca2+ channel: from discovery to new signaling concepts’ Journal of Neurochemistry, Vol 102, Issue 5 Page 1426-1446 Phospholipase C (PLC) mediated hydrolysis of PtdIns(4,5)P2 Biol 2056 generates two second messengers: Diacylglycerol (DAG) and 2024 L2+3 inositol(1,4,5)P3 (ins(1,4,5)P3) a1 adrenergic Membrane bound Synthesis of PtdIns(4,5)P2 Receptor Second messenger PI4K PIP5K Diacylglycerol (DAG) PLC inositol(1,4,5)trisphosphate (Ins(1,4,5) Cytosolic Second messenger Protein kinase C is a major downstream target activated Biol 2056 in response to increases in Diacylglycerol (DAG) 2024 L2+3 The PKC family are serine threonine kinases DAG and Ca2+ dependent (cPKC) or DAG dependent (nPKC) Pseudosubstrate (like PKA) inhibits enzyme activity. Interaction with DAG at the membrane and Ca2+ induces conformational change and relieves pseudosubstrate inhibition. PKC are also regulated by a family of binding proteins called RACK (receptor for activated C-kinase) which akin to AKAP regulate subcellular distribution and downstream phosphorylation. Ion channels (heart for example) RAF/MEK/ERK pathway Src non receptor tyrosine kinase Cell cycle regulators Nuclear lamins required for nuclear envelop breakdown  Activation of Gaq and PLC underlie smooth muscle cell contraction Biol 2056 in response to adrenergic stimulation through the a1-receptor 2024 L2+3 g b Gaq Gaq Phospholipas smoot eC (GDP) (GTP) g h b Heterotrimeric G-protein Dissociation (PLC) muscle Ins(1,4,5)P3 DAG (diacylgyclerol) cells Increased Ca2+ contraction IP3 receptor Ca-Calmodulin Dependent PKC Contraction and Kinase (CAMK) Vasoconstriction P P Ca2+ Myosin Cytoskeletal Sarcoplasmic Light chain (MLC) components reticulum Kinase P MLC MLC Actin Adrenergic stimulation through the a1-receptor also (remember b- Biol 2056 receptor) regulates glycogen breakdown through Gaq and PLC 2024 L2+3 activation Phospholipas IP3 receptor eC (PLC) Ca2+ Ins(1,4,5)P3 DAG (diacylgyclerol) Sarcoplasmic reticulum Ca2+ Liver a a Glycogen d subunit is calmodulin g d d g PKC breakdown b b Ca2+ b b Phosphorylase d d Glycogen synthase kinase – a hexa- decamer g g active a a P glucose P Glycogen synthase inactive Phosphorylase a glycogenolysis  Adrenergic agonist derived responses can be split according to the Biol 2056 activation of at least two different receptor dependent pathways. 2024 L2+3 Adrenergic stimulation (in vivo and in vitro assays) Alpha adrenoreceptors Beta-adrenoreceptors smoot Skelet h Adipos Cardia Liver al muscle e c cells Glycogen muscle cells breakdown Lipolysis Increased Increased contraction contraction Contraction andIncreased heart rate glucose Free fatty acids Increased Vasoconstriction Increased force Excitation/ Contraction coupling uist R.P. A Study of the Adenotrophic Receptors, Am. J. Physiol. 1948 153:586-600  Biol 2056 her effectors of cAMP signalling: more than just PKA 2024 L2+3 Guanine nucleotide Exchange protein activated by cAMP Regulation of; RAPGD RAPGT Cell Adhesion EPAC Insulin secretion P P Cell junctions MAPK cAMP- PKA R C C Protein P Many outputs R C C cAMP R CREB Transcription R cAMP Cyclic nucleotide gated channels Positive ions In and out HCN channel in heart P: More than just PKA. Biol 2056 C couples cAMP signalling to regulation of cell adhesion and secretion. 2024 L2+3 cAMP EPAC Exchange Protein directly Activated by cAMP) inactive active Regulation of; RAP GD RAP Cell Adhesion GTP Insulin secretion P Cell junctions GTPase activating proteins (GAPS) 1. EPAC is a guanine nucleotide exchange factor (GEF) that binds cAMP which induces a conformational change to activate its GEF activity 2. EPAC directly EPAC has a lower affinity for cAMP than PKA: might only be activated at high concentration 3. It activate the small molecular weight g protein RAP (not the same as a heterotrimeric g protein. It is like Ras) 4. RAP acts as a molecular switch to regulate cytoskeletal dynamics, cell adhesion  Biol 2056 can respond to a large range of diverse molecules with very diverse sizes. 2024 L2+3 Small molecules Acetylcholine 1. 7 transmembrane Histamine 2. Largest family in the Peptides genome (approx Adrenaline Bombesin 1000) Nor adrenaline Angiotensin 3. Fast (some involved in Glutamate opioids vision, smell, taste) ATP adenosine 4. Ligand interaction pids induces a conformational nandemide (CB receptor) change in receptor rostanoids (prostaglandins 5. GEF activity of the hromboxane) receptor induces a PA (lysophosphatidic acid) switch in GTP binding of the alpha subunit 6. Both alpha and the Chemokines beta/gamma subunits can signal C-C 7. Alpha subunits can be C-X-C (IL8) stimulatory and inhibitory Glycoproteins light 8. Switched off by FSH (28KDa) taste intrinsic GTPase TSH odours 9. Receptor  GPCR signalling leads to the activation of diverse reversible protein Biol 2056 phosphorylation cascades 2024 L2+3 Cell type specific igands and receptors b Ga Ga s q g cAMP IP3 DAG PIP3 Generic signalling Ca2+ modules PKA CaMKs PKC PKB PDK1 aPKC P Common and cell Common and cell type specific reversible phosphorylation Type specific outputs CaMKs Ca2+-dependent protein kinases, PKA; protein kinase A (etc), aPKC; atypical PKC not activated by DAG: Multiple diverse inputs are transduced by a limited number of Biol 2056 transduction cascades but can lead to a diverse array of output 2024 L2+3 responses. 1. Different GPCR activation in GPCR the same cell that increase cAMP can elicit the same downstream output 2. The same GPCR in different PKC, Ca2+ cAMP cell types can elicit cell type specific outputs. This might be the consequence of tissue specific expression of downstream targets (phosphorylase kinase (liver) versus HSL (adipose))  Biol 2056 2024 L2+3 Supplementary slides  Biol 2056 2024 L2+3 TARGET TISSUE HORMONE MAJOR RESPONSE Thyroid gland thyroid-stimulating thyroid hormone synthesis hormone (TSH) and secretion Adrenal cortex adrenocorticotrophic cortisol secretion hormone (ACTH) Ovary luteinizing hormone (LH) progesterone secretion Muscle adrenaline glycogen breakdown Bone parathormone bone resorption Heart adrenaline increase in heart rate and force of contraction Liver glucagon glycogen breakdown Kidney vasopressin water resorption Fat adrenaline, ACTH, triglyceride breakdown glucagon, TSH GPCR that regulate cAMP synthesis, some targets phosphorylated by PKA and specific tissue outputs mples of GPCR ligands that activate Gaq to regulate PLC signalling Biol 2056 2024 L2+3 Differential signalling outputs can be attained by tissue selective Biol 2056 receptor subtype expression 2024 L2+3 Adrenergic a1 a2 b1 b2 b3 Receptor subtype Ateriolar smooth vasoconstriction in Vasodilation muscle tissue (other than (skeletal skeletal muscle and muscle liver) liver) Bronchiolar dilation Heart Increased heart rate Skeletal muscle glycogenolysi s Liver glycogenol Glycogenoly ysis sis Gluconeogen esis Adipose Inhibition lipolysis of lipolysis