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BIOCHEM Lecture 06
exam 2
| Question | Answer |
|---|---|
| cell signaling definition and purpose | allows cells to sense and respond to the environment |
| signal | chemical ligands or pressure light and temperature |
| receptor | recognize signal and passes on the signal intracellularly |
| cell surface receptors | on the plasma membrane, trigger a second messenger for intracellular signaling |
| intracellular receptors | in the cytosol or nucleoplasm, attach to ligands to activate and become a transcription factor |
| signal transduction receptors | passes signal along with an enzyme cascade, activates effector protein to alter cell activity |
| non-signal transduction receptors | channel proteins don't change conformation but move solutes down a concentration gradient |
| second messenger | activated by receptors and relay signal within the cell EX: cAMP, calcium ions, IP3, DAG |
| non-polar signaling | pass through lipid bilayer by binding to intracellular receptors, trigger transcription of specific genes |
| ligand-gated ion channels | 1) ligand binds to channel protein 2) channel opens 3) ions move through channel down a concentration gradient |
| signal transduction | signal is carried by pathway with a series of proteins, each protein alters conformation of the next, activates effector protein to alter cell activity EX: GPCR and RTK |
| amplifying signals | kinases transduce signals and multiple kinases can be activated at each step |
| phosphorylation | kinases are phosphorylating enzymes that activate other kinases to cause phosphorylation cascade, this is important for amplifying the signal to transfer it through the cell |
| G-protein coupled receptors | contains 7 transmembrane helices |
| G-protein | subunit proteins |
| G-protein enzyme | the alpha subunit GTPase converts GTP into GDP to restart pathway |
| GPCR signaling (1-4) | 1-2) ligand binds to receptor, increases intracellular affinity, attracts G-protein GDP 3-4) G proteins are activated, GDP dissociates, GTP binds |
| GPCR signaling (5-6) | 5) active G proteins pass along the signal to the effectors 6)alpha subunit of G protein hydrolyses GTP into GDP and G protein subunits start cycle over |
| phospholipase C pathway (1-4) | 1-2) extracellular signal binds to GPCR attracting G-protein-GDP 3)G protein exchanges GDP for GTP and dissociates 4)alpha-G-protein GTP activates phospholipase C |
| phospholipase C pathway (5-8) | 5) active PLC cleaves PIP2 into IP3 and DAG 6-7) IP3 triggers calcium release from endoplasmic reticulum 8) calcium and DAG activate protein kinase C which causes a phosphorylation cascade |
| cAMP pathway (1-4) | 1-2) extracellular signal binds GPCR attracting G-protein-GDP 3)G-protein exchanges GDP for GTP and dissociates 4) alpha-G-protein-GTP activates adenylate cyclase |
| cAMP pathway (5-6) | 5)active adenylate cyclase catalyzes conversion of ATP to cAMP 6)cAMP activates kinase cascade |
| receptor tyrosine kinase pathway | 1) ligand binds to 2 RTKs 2) receptor dimerization 3) receptors trans-auto-phosphorylation 4) receptors bind and activate effector proteins via phosphorylation |
| ligand | the chemical signal that binds to the receptor |
| kinase | enzyme that phosphorylates, involved in PLC signaling, cAMP pathway, RTK pathway, Ras-MAP kinase pathway |
| cAMP | second messenger, involved in G-protein adenylate cyclase pathway, activates kinase cascade |
| DAG | second messenger, involved in phospholipase C pathway, activates protein kinase C to cause phosphorylation cascade |
| Ca2+ | second messenger involved in phospholipase C pathway, calcium activates protein kinase C to cause phosphorylation cascade |
| IP3 | second messenger, involved in phospholipase C pathway, triggers calcium release from endoplasmic reticulum |
| channel protein | pathway for solutes to move into a cell down a concentration gradient, ligand gated ion channels |
| Ras | activation of Ras causes kinase cascade in MAPK pathway |
| effector protein | alter cell activity, involved in cell surface receptors, RTK pathway, Ras-MAP pathway |
| RTK | regulate cell growth, division, differentiation, survival and migration, signal transduction RTK pathway |
| stimulus | first messenger |
| conformation | shape of the receptor, signal transduction alters proteins |
| MAP | kinase enzyme that phosphorylates MAPKKK to MAPK |
| phosphate | added through phosphorylation in signal transduction |
| phospholipase C | enzyme that cleaves PIP2 into secondary messengers in PLC pathway |
| PIP2 | molecule broken into IP3 and DAG in PLC pathway |
| protein kinase C | second messengers activate the enzyme to cause phosphorylation cascade in PLC pathway |
| adenylate cyclase | enzyme that catalyzes the conversion of ATP into cAMP |
| kinase cascade | amplifies signal, occurs in cAMP pathway and Ras-MAP kinase |
| dimerization | brings receptors together in RTK pathway |
| scaffolding | localizes proteins in a pathway to prevent upstream activators from reacting with downstream activators |
| cross pathway inhibition | other pathways with common components are actively inhibited by the activated pathway. |
| endoplasmic reticulum | calcium released from ER in PLC signaling to activate protein kinase C |
| specificity: receptor expression | different cells have different receptors and are expressed at different times |
| specificity: scaffolding | localizing proteins and prevents upstream activators from interacting with downstream proteins |
| specificity: cross pathway inhibition | other pathways with common components are inhibited by the activated pathway |
| divergence | a single stimulus sends signals along a variety of different pathways |
| convergence | different receptors bind to different ligands but lead to the same effector |
| crosstalk | interaction between multiple signaling pathways |
Created by:
r.logan6029
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