Lecture 18 and 19 - Signal Transduction Receptors and Intracellular Calcium Flashcards
1) Where are Ca+2 ions stored?
2) Is ATP required for pumping Ca+2 in for storage and why?
3) What’s one transporter mech Ca+2 ions use to get outside of cell
4) Is the Ca+2 ion concentration higher intracellularly or extracellularly?
5) Why does cell invest ATP to pump Ca+2 outside cell?
6) What group is Ca+2 ions part of?
7) What’s the simple relationship btw Ca+2 ions and G protein?
1) ER
2) yes because Ca is going against it’s concentration gradient (storage site for Ca so there’s a high concentration in ER)
3) coupled transporter with Na+ ion - antiporter –> Na+ driven exchanger (Na/K pump created [Na] gradient outside of cell, so then Na ions can come into the cell in exchange for Ca ions leaving
4) extracellularly
5) wants to maintain concentration gradient and rid cytoplasm of Ca+2
6) second messengers
7) Ca+2 ions can be released from ER under certain circumstances such as activation of a G protein complex
Describe the intracellular Ca+2 signaling involving G protein complex
1) Which specific alpha subunit is used for this pathway?
2) What does G protein activate?
3) What is it’s general fn?
4) What does it do in this pathway?
5) What is the result of this action (in relation to DAG and IP3?) What does this make them?
6) What does the IP3 mol do?
7) What is not pictured on ER?
8) What is the result of this action in relation to Ca+ ions?
9) What does Ca+ do in combination with another mol?
1) Gq alpha subunit
2) phopholipase C
3) lyses phospholipids at serine and threonine residues
4) lyses Pl 4.5-bisphosphate into DAG (diacylglycerol) and IP3 (1,4,5-trisphosphate) mols
5) increases concentration of DAG and IP3 in cytoplasm –> 2nd messengers
6) binds to IP3-gated Ca+2 release channel on ER and opens the channel allowing Ca+2 to be released into cytoplasm
7) Ca+2 pump which transports Ca+2 into ER
8) increases [Ca+2] in cytoplasm –> 2nd messenger
9) Ca+2 with DAG activate PKC
Describe the activation of Calmodulin-dep protein kinase
1) Describe how calmodulin-dep PK appears in its inactive form.
2) What happens to the calmodulin mol?
3) What does the calmodulin mol do?
4) How does PK respond?
5) What happens to calmodulin/ca?
6) True or False: PK is fully active with calmodulin/ca bound
7) Eventually what happens with [Ca+2] and PK?
1) PK has a catalytic and an inhibitory domain. Catalytic domain is attached to the inhibitory domain in inactive form
2) Ca+2 binds to calmodulin and turns it into its bound form
3) Calmodulin/ca binds to inhibitory domain on PK which activates the PK –> catalytic domain is released from attachment site and grows a “bulge”
4) PK autophosphorylates to fully activate itself
5) Calmodulin/ca are released from mol
6) False. not fully active until it autophosphorylates
7) [Ca+2] gets too high –> Ca pumps –> [Ca+2] drops –> no ca to bind to calmodulin…etc –> protein phosphatase becomes active and dephosphorylates cal-dep PKm –> inactivates
1) What is Lethal White Foal Syndrome
3) Why is mom brown with white spots and foal is white?
4) What is the result of this mutation?
5) Explain mutation - why no migration
***type of Ca+2 signaling was working during development, takes hrs - prolonged Ca+2 signaling
1) Neural crest signaling in development –> become melanocytes which eventually migrate to skin (color) and develops enteric NS (neural crest cell proliferation is a rise in [Ca+2]
2) White color due to a lack of melanocytes
3) Mother - American paint horse –> heterozygous for mutanous gene whereas foal is homozygous for mutanous gene (no migration of melanocytes –> all white)
bred 2 heterozygous horses–> 1 in 4 chance of producing a foal that is homozygous for mutanous gene
4) no neural crest migration for melanocytes as well as little or no development of enteric NS –> foal will die of eternal constipation (colic) because no control of NS
5) mutation in G protein receptor - EDNRB is gene (becomes activated during neural crest cell development) which eventually activates phospholipase C
- mutation leads to dominant frame overo pattern as well as overo lethal white foal syndrome
1) What are some other patterns of american paint that can interfere?
2) Whats the general point?
1) tobiano, tovero, fram overo, calico/sabino, medicine hat
2) can’t always predict whether a mother will produce a lethal gene(mutation) –> genetic test
1) Can muscle cells/tissues use same time-scale as Ca+ signaling of neural crest cell development?
2) What type of receptor do muscle cells use?
3) What happens first?
4) What does the receptor do?
5) What happens everytime a muscle contracts
6) What does flooding of Ca+2 in myoplasm cause?
1) no, because it takes hrs and muscles need a quicker response –> every time a muscle contracts, [Ca+2] fluxuates
2) cell surface receptor –> voltage-gated Ca+2 channel
3) Depolarization of plasma membrane –> activates Ca+2 receptor
4) it interacts with Ca+2 release channel on ER in sarcolemma –> activates and opens it –> Ca+2 are released’
5) [Ca+2] increases and then returns to resting [] when releaxes
6) activation of contractile proteins
1) What do halogenated anesthetics (halothane and isofluorane) do?
2) What is the result of this?
3) What does this cause?
4) What can you use heat to combat?
1) accentuate the effect of naturally-occuring mutations in sarcoplasmic reticulum calcium channel
2) excessive and uncontrolled ca channel opening and increased myoplasmic ca concentrations –> leaky Ca+2 channel
3) mucle contracture which in turn increases metabolism to regenerate ATP and generate heat
4) shaking –> generate heat –> combat hypothermia
Describe the pathway for activating GF receptor kinases
1) What type of receptor is it?
2) What happens next?
3) How does receptor respond?
4) What can now happen?
1) enzyme-linked receptor (2 sep subunit united by binding of mol)
2) extracellular GF binds to receptor stimulating its tyrosine kinase domains (can phosphorylate tyrosin residues)
3) autophosphorylates at all 4 catalytic domains –> activates itself
4) Can use phosphorylated sites as attachment pts for binding proteins
***binding proteins can only associate once domains are phosphorylated (on receptor)
1) What’s one type of binding protein that interacts with a phosphorylated site on activated receptor tyrosine kinase?
2) What does that bound mol do?
3) What happens next?
4) What is a Ras protein?
5) What does the Ras protein do?
1) an adaptor protein binds to phosphorylated site
2) It attracts a Ras-activating protein and interacts with it
3) Ras-activating protein interacts and stimulates the inactive Ras protein
4) a different type of G protein (diff then heterotrimeric one)
5) It loses its GDP and gains a new GTP thereby becoming active –> goes to activate something else
1) What’s one enzyme Ras protein can activate?
2) What does MAP stand for? What is it involved in?
3) What does MAP-kinase x3 do?
4) What happens as a result?
5) What is the last step?
6) What is the end result?
7) What does the phosphorylation ot each protein do?
8) True or False: All the MAP-kinase proteins discussed are all the same protein continually being phosphorylated
9) What mol works more or less by this mechanism?
1) MAP-kinase-kinase-kinase
2) Mitogen-activated protein; involved with cell cycle
3) phosphorylates another member of cascade pathway –> MAP-kinase-kinase
4) MAP-kinase x2 phosphorylates TWICE MAP-kinase (have two P gps on it now)
5) MAP-kinase can translocate to nucleus and phosphorylate proteins there (nuclear gene regulatory protein) or stay in cytoplasm to do work (cytostolic/membrane protein)
6) rapid change in activity of cytostolic or membrane proteins; changes in gene expression
7) activates the protein
8) False, each are individual/unique proteins
9) insulin
1) Describe an example of GF receptors gone wrong
1) EGF receptor - epidermal growth factor normally has a extracellular ligand-binding domain where GFs bind and activates the intracellular tyrosine kinase domain
2) mutation occurs –> truncated extracellular domain
3) extracellular receptor is removed –> GF can’t bind and regulate signal cascade
4) intracellular tyrosine kinase is always turned on –> Ligand-independent
5) Dimerizes and activates itself so its always turned on and goes on to stimulate cellular activities, cell proliferation, migration (oncogenic –> lack of control of cellular proliferation)
1) Give two sites where acetylcholine can bind
2) Describe the receptor and effect for each site
3) True or False: hormones can bind to multiple receptors
4) How can acetylcholine have 2 different effects?
1) heart muscle cell and skeletal muscle cell
2) Heart muscle - G protein receptor –> acetylcholine binds –> decreased muscle contraction
Skeletal muscle - Acetylcholine gated ion channel receptor –> acetylcholine binds –> increased muscle contraction
3) True
4) different receptors mediate different effects on a cell
True or False: Membrane phospholipids can also act as signaling mol
True or False: Fatty acid chains are randomly esterified to membrane phospholipids
1) What does C2 on glycerol commonly have?
2) What happens at this site?
3) What is this phospholipase controlled by?
4) What is AA the starting point for?
True
several phospholipases can attack phospholipid in lots of places –> specific places where they can attack
False
1) more often has an unsaturated fatty acid
2) Phhospholipase A2 will cleave off thsi FA and often produce Arachidonic acid
3) by hormone-receptor signal transduction
4) many lipid metabolites involved in blood clotting and inflammation —> eicosanoids and prostaglandins
PKA, CaM-kinase, PKC, MAP kinase and PKB all have effects on gene regulatory proteins and cytosolic or membrane proteins
Remembering the G Protein Cycle…..
1) How does Cholera disrupt this cycle?
2) What other toxins effect a G protein in the same way?
1) Cholera secretes cholera toxin which transfers an ADP ribose gp to the G protein alpha subunit (gets it from NAD+ –> nicotinamide)
2) inhibits the enzyme that turns off G protein (inhibits GTP hydrolysis) –> G protein stays in GTP bound state
3) G protein doesn’t turn off –> inc adenylate cyclase –>< inc cAMP –> inc PKA –> epithelial cells secrete water –> diarrhea
2) pertussis toxin (whooping cough) and diptheria toxin; don’t target same G protein, but same process
