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Cell Bio 380 > exam 2 > Flashcards

exam 2 Flashcards

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1
Q

process of exportig mRNP from the nucloplasm to the cytoplasm

A
  1. gle-2 sits on the nuclear basket and recognizes NXF and helps push it into basket
  2. the FG nuclearporins recognie NXT and help push it through the main part of the NPC
  3. DBP5 is an enzyme that sits in the cytoplasmic filiments and helps pull off proteins with the use of ATP
    1. nxf nxt and REF will recycle back through NPC
  4. once mRNP gets into cytosplam CBC is replaced with elf 4 and pabpII is replaced with PAbp1 in order to translate properly
    1. elf4
      1. eukaryotic initiation factor
        5.
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2
Q

process protein imort into nucleus

A
  1. the cargo binds to imortin w/NLS and heeads trhough the NPC
  2. the FG nuclear porins recognise imprtin and allow the cargo complex to go through the NPC
  3. once the cargo complex is in the cucleus GEF will conver ran GDP to Ran GTP
  4. Rangtp will bind to importin and free the cargo
  5. ran GTP wiht importin will go back thorough the NCP
  6. once in the cytoplasm GAP will trigger ran to hydrolyze from GTP to GDP and will let go of importin
  7. ran GDP goes back into the nucleous through the NPC
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3
Q

process of protein export out of nucleus

A
  1. ran GTP binds to exportin and exportin will bind to the cargo wich has a NES and head through the NPC
  2. once in the cytoplasm GAp will triger RAN GTP to hydrolyze gtp to gdp and the cargo comolex will seperate
  3. the cargo is free to do its function
  4. exportin and ran GDP will go back through the NPC individually
  5. GEF converts ran GDP back to ran GTP
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4
Q

process of protein import into mitochondria

A
  1. in the cytoplasm HSC70 will bind to a protein using ATP to linearize it section by section
  2. in the outer membrane of the mitochondria tom 20 will recognize and bind to the Matrix targeting sequence within the protein and hold onto it
  3. it will then pass it onto tom40
  4. tom 40 will begin pushing the protein through the outer membrane and hsc70 will leave section by section
  5. TOM and Tim proteins will hold the two membranes closer to create a contact site
  6. tim 23 will recognize the MTS and pick up the protein from TOM40 and push it through the inner membrane
  7. tim 44 which is next to tim 23 has an hsc70 attatched to it in the matrix and will atatch it to the protein so it doesnt fold too soon
  8. a protease will cleave off the MTS
  9. HSC 70 will un bind and the protein will fold and function
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5
Q

stop transfer pathway

A
  1. a protein with a matrix targeting sequence and stop transfer sequence will have hsc70 bind to it section by section suing ATP to linearize it
  2. in the outer membrane of the mitochondria tom 20 will recognize and bind to the MTS then transfer it to TOM40
  3. tom 40 will pass it through the outer membrane and as it goes trouhg hsc70 will come off section by section
  4. tim and tom proteins will creat a contact site and hold the two membranes close to gether
  5. tim23 will recognize the MTS and and start to move it through the inner membrane
  6. in the matrix tim44 which is next to tim23 will have an hsc70 attatch to the protein using ATP to keep it linerarized as it comes out as to not hae it fold too soon
  7. a protease will cleave off the MTS and the hsc70 wil leave
  8. Tim23 will recognize the stop transfer sequence and will undergo a conformation change and push the stop transfer sequence into the inner membrane
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6
Q

oxa pathway

A
  1. a protein with a MTS and an OXA targeting sequence will have HSC70 bind to it using ATP to linearize the protein for transprot
  2. Tom 20 will recognize the MTS and bind to it then pass it to TOM40
  3. tom40 will begin to pass it through tthe outer membrane and HSC 70 will fall off section by section as it passes throguh
  4. tom and tim proteins will hold the two membranes close together creating a contact site
  5. Tim23 will recognize the MTS and grab the protein and push it trough the inner membrane
  6. Tim44 will attatch hsc40 using atp to keep it linear
  7. once the protein is full in the matrix a protease will kleave off the MTC and the hsc70 will leave allowing the protein to fold
  8. once its folded the OXA translocator in the inner membrane will recognize the oxa targeting seuence and grb it
  9. it will then go through a conformaton change and insert only the oxa targeting sequence(hydrophoboic) into the membrane
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7
Q

Multipass Pathway/ TIM22 pathway

A
  1. a protein with no MTS but with multiple internal targeting sequences (hydrophobic) will have hsc70 attatch using ATP to linerize
  2. tom 70 will recognize the internal targeting sequence
  3. then pass it onto tom40 which will pass it through the outer membrane
  4. as it passses hc70 will leave section by section
  5. tim22 will recognize the internal targeting sequence
  6. tim22 will undergo confermation change anf insert the hydrophobic parts into the innermembrne
  7. while its doing that it will utalize tim9/10 to help prevent folding
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8
Q

what is needed to put a protin into the outer mitochondrial membrane

A

it requires TOM40 and SAM to work together

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9
Q

intermembrane space pathway

A
  1. a protein that has an intermembrane space targeting sequence and a matrix targeting sequence will have HSC70 bind to it via ATP to lineaize the protein
  2. Tom20 in the outer membrane of the mitochondria will regognize the MTS and grab the protein
  3. it will then pass the protein to tom40
  4. tom40 will push the protein through the outer membren and as it passes hsc70 will come off section by section
  5. tim 23 will recognize the MTS nd pick it up
  6. the IMSTS will trigger tim 23 to go through a conformation change and embed the sequence into the inner membrane
  7. a protease in the inner membrne will cleave off the MTS and cut the hydrophilic part from the hydrophobic part
  8. the hydrophilic part of the protein will now fold and function while the hydrophobic part will get degraded
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10
Q

tim 9/10 pathway

A
  1. a protein with a targeting sequence will have hsc70 bind to it with atp to linearize the protein
  2. it will then go directly through tom40 through the outer membrane
  3. Mia and erv enzymes in the intermembrane space will grab hild of the protein and foldit so it cant go through another translocation
    1. it will keep it folded via disulfide bridge (covalent bond)
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11
Q

transporting proteins to the chloroplast thylakoids

A
  1. a protein with a Stromal import sequence and thylakoind targeting sequence following the stromal import sequence will have HSC70 bind to it via ATP to linearize the protein
  2. TOC will recognize the SIS and pass it through the outer membrane
  3. proteins in the contact site will hold the two membranes closer together which will allow tic to grab the protein and move it into the stroma
  4. hsc70 will bind to the protein in the stroma
  5. the stroma targeting sequence will get cleaved off in the stroma with a protease
  6. if it has a TTS it will proceed via SRP path way
  7. if it has a metal bound protein it will proceed via the metal bound protein pathway
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12
Q

SRP pathway

A
  1. once a protein with a thylacoid targeting sequence is in the stroma it needs to get into the thylacoid
  2. it requires a chloroplast SRP which will bind to the TTS and bind to the SRP receptor in the thylakoid membrane
  3. it will then be transfered to the thylakoid membrane translocator and HSC70 will leave as it pushes it into the thylakoid
  4. a protease will cleave off the thylakoid targeting sequence and the protein can function in the thylacoid
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13
Q

Metal Bound Protein Pathway

A
  1. Metal Bound Protein Pathway occurs if the folded protein needs to go to the Thylakoid
  2. Metal-binding proteins will bind to metals such as Cu or Fe
  3. Once the Metal-binding protein gets into the stroma it will find those metals and bind to them and folds the protein
    • Cannot go through the thylakoid membrane translocator folded
  4. As long as there is the Metal Bound Protein signal the Metal Bound Protein Translocator will move the folded protein through the thylakoid membrane.
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14
Q

clathrin coat

A
  • formed at the cell membrane or the golgi apparatus (trans side )
  • destination lysosome ccell membrane or golgi
  • clathrin is made up of a triskelion (3 protein chain ) which bind together to form a basket like structure
  • receptors and ARF are embeded in the membrane the receptors are targeted for bringing in specific cargo molecules from outside the cell into the cytosol
  • once the receptots are bound to the cargo it attracts the ap complex which attracts clathrin
  • Arf Gtp will the be hydrolyzed to arf GDP and dissasemble the ap complex and clathrin
  • the arf GDP will become soluable
  • using GTP dynamin will assist the clathrin separtation of the vesicle
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15
Q

COPII coated vesicle

A
  • formation at the RER destination GOlgi
  • SAR1-GDP will float aroun untill it finds a GEF called Sec12
  • sec 12 will activate Sar1 GTP by taking of the GDP and putting on a new GTP
  • Sar1GTP will activate and undergo conformation change which will expose its hydrophobic tail and ebed it into the RER membrane
  • multiple Sars will embed in the membrane and create an infoldng into the cytoplaasm
  • then receptors sitting inside the membrene facing the ER Lumen will bind to cargo destined for the Golgi apparatus
  • there are soluble proteins that float into the vesicle and integral proteins that will also be transported into the golgu
  • Sar1 will then attract Sec23/sec24 proteins that make up the COPII coating and bind to which will for the vesicle
  • sec23and sec24 trigger the pinching off the vesecle into the cytoplasm
  • once its ponched off sar1 will hydrolize and to form Sar1 gdp and the hydrophilic tail will dissasociate from the vesicle and caude the COPII coat to dissasemble
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16
Q

Formation of COP I

A
  1. formed at the golgi(cis side) and destined for ER
  2. uses ARF GDP the GEF converts to arf GTP
  3. hydrophobic tail will inbed into the golgi membrane
  4. multiple arfs will imbed and caus and infolding into the cytopasm
  5. COPI proteins will attatch and cause the vesicle to pinch off
  6. arf GTP wil hydrolyze from gtp to gdp and dissasembel to the cop 1 proteins
  7. will transfer to the ER
17
Q

resdent signals

A

signals on proteins that tell where they belong

KDEL _ is only for soluble proteins that are hydrophilic not imbeded in the membrane

KKXX is only for integral proteins associated with the membrane (CopII)

18
Q

docking a vesicle

A
  1. an uncoted cesicle exposes the proteins needed to dock
  2. RAB GTP will hae a hydrophobic tail embeded in the membrane
  3. vsnair protains will also be embeded
  4. in the target membrane there will be Tsnares and rab effector
  5. the RABGTP will dock on the Rab effector and will bring the membranes close together
  6. thiss will allwo the v snairs and t snairs to come in contact and interlock anchoring the vesicle tightly to the membrane
  7. Rab GTP will hydrolyze and become soluble where it will eventualy use GEF to convert it back to GTP to bind to a new vesicle
  8. the vesicle and target membrane will fuze and allow anything transported in the vesicle to go into the target oragnelle
  9. NSF with the use of ATP will separate the vsnares and T snares
  10. the vesicle will become part of the membrane of the target organelll
  11. the v snares will have a KKXX signal and then tansport back to the Er via a COPI vesicel
19
Q

paracrine signaling

A
  • a celll will release signal molecules into the extracelllar environment and the signals will diffuese to nearby cells
  • any of the near by cells that have the receptor will bind to the signls
  • multiple cells can be influenced by one signaling event
20
Q

autocrine signaling

A
  • the cell releasing the signal must have the receptor for that signal molecule a
  • to doublle check the mechamism works
21
Q

synaptic signaling

A
  • neuron with the axon terminal has synaptic vesicles the release a chemical signal that travels across and binds to the receptor on the target cell
  • one communicating cell can only affect one target cell
  • the ration is 1:1 limtied and focused signaling
22
Q

cell surface or cell to cell signaling

A
  • signal molecule is embeded in the membrane of the cell receptor on the reciving cell must find it along the surface of the communicating cell
  • not common becuase cells must be adjacent
23
Q

hormonal signaling

A
  • multiple cells are releasing signal molecules to affect target cells at a distance
  • need a larg amout of signal and must trave far distances
  • signals trave to blood stream to get to target cell
  • can affect target in multiple destinations
24
Q

Gprotein linked receptor

A
  • function
    • to serve as an intermediate between the first signal and creat a second messanger which will communicate with the internal part of the cell that a signal had been communicated so the cell can respond
  1. inactive Gprotein at the cell membrane at the cytoplasm
  2. a receptor on the cell membrane will bind to a signal molecule (1st messenger) and ndergo a conformation change
  3. this allows the g protein to bind to the active receptor and converts the inactive protein into n active Gprotein bu converting from GDP to GTP
  4. the alpha subunit undergoes a conformation change and moves away from the beta gama ubunit and the g protein becomes activated
  5. the activated alpha subunit g protein will bind to the enzyme adenylin cyclase and create a second messanger to comununcate with the internal part of the cell that a signal was recived at the cell surface
  6. activated adenylyl cyclase will catalyze a reaction that will convert ATP to CAMP (secondary messanger)
  • other enzymes
    • the activated g protein will bind wih tthe enzyme phosolipse C and search for a 4,5 phosoinositol biphosphate and cut the molecule into 2 peices
      • Diacyglycerol DAG -stays associated with membrane
      • inositol triphosphate IP3
25
Q

CAMP activation of protein kinase A (PKA)

A
  • all kinase phosphorylate something to activate it (adds phosphate)
  • regulatory subunits are bound to the catalytic subunit to keep protine kinase A inactive
  • cAMP formed ny adenylyl Cyclase will bind on the camp binding site
  • the regulatory subunit will go through a conformaton change and kick of the catalytic units and activate
  • they will travel into the nucleous to find CREB and will phosphorylate and activate CrEB
  • the catalytic units will return to its binding units
  • activated creb will find the CrEB binding elements on the DNA and bind wich will activate transciption
    • mRNA –> ptotein
26
Q

DAG and IP3 activation of protein Kinase C

A
  • insotil triphosphate will float untill it reached the SER membrane to bind to an IP3 receptor (chemically gated chanell )
  • opens the Ca++ channel and releases Ca++ into the cytoplasm
  • proteine kinase C must bind to Diacyglyceral(DAG) and a Ca++ (needs both 2ns messangers)
  • proteine kinase C goes through confirmation change and is now active
  • PKC will phosphorolate other proteines
  • to reset the system
    • CA++ is removed and reters back to SER via Ca++ pump
    • PKC will leave and become inactive
    • IP# will Rejoin with DAG
27
Q

Tyrosine Kinase Receptors

A
  • the receptor is fornd in the membrane as an inactive monomer
  1. a growth factor signals will bind to two monomers and and cause them to come to gether and dimerize
    1. a conformation change will occur and the activate tyrosine kinase (enzyme activity
  2. autophosphorylation occurs
    1. each enzyme monomoer phosphorylates the other monmomer on tyosine amino acids
    2. an adaptor protein will bind to the phosphate
    3. a ras GEF will bind to the adaptor and will activate Ras
      1. ras is a membrane assosicated protein and is in the genreal area
      2. ras gef will remove GDP and pyt on a seprate GTP
    4. activated Ras acts as a second mesanger
    5. ras activates the MAP kinase pathway
    6. RAS will activate RAF (kinase)
    7. RAF will phosphoralate MEK on serine/threonine amino acids
    8. once MEK is activated it will phosphoralate MAP KINAse
    9. active MAP kinase will follow 1 of two pathways
      1. phosphorylates protein to change its activity
      2. phosphorylates transcription factor to chang fene expression
28
Q

Receptor Locations

A
  • Cellular Membranes
    • Used when the signal molecules are hydrophilic
  • Intracellular Receptors
    • For steroid and other hydrophobic signal molecules
29
Q

Receptor Regulation

A

· Signal Molecules can only act when bound to a receptor

· Anything that changes the number of receptors or their availability to bind to signals affects communication

30
Q

Sequestration of receptors

A

(pulled away from membrane)

  1. The target cell can pull away receptors from the membrane by enfolding to form a vesicle
  2. The vesicle pulls away from the cell membrane and receptor are trapped

Can not be activated or can not communicate if signal is already bound

  1. Temporary as vesicle can rejoin the membrane
31
Q

: Receptors Downregulation

A
  1. The target cell can pull away receptors from the membrane by enfolding to form a vesicle
  2. The vesicle pulls away from the cell membrane and receptor are trapped
  3. The vesicle will fuse with the membrane of a lysosome if the cell does not want to put back those receptors

o Degradation of the receptors will occur

· Long term response

· New receptors must be synthesized in order to replace degraded receptors

32
Q

Receptors Inactivation

A
  1. Binding an Inhibitory Protein to the receptor to inhibit the formation of second messengers by:

o Changing conformation so a signal cannot bind

o Signal can bind but inhibits activation

· Short term response

· Reversible by removing the inhibitory protein

33
Q

Inactivation of Signaling Protein

A
  1. A signal bound receptor will activate the signaling protein (second messenger or G-Protein)
  2. BUT the signaling protein has a Inhibitory protein bound to it so it stops the activation process
34
Q

Inhibitory Protein Production

A
  1. An activated receptor activates the signaling protein
  2. Signaling protein activates an Enzyme but an Inhibitory protein is formed
  3. The Inhibitory protein will inhibit the same type of receptor or second messenger processes
35
Q

Signal Release

A

· The more signals the more the communication

· Anything that affects the amount of signal produced or released will influence communication

o Increased communication

o Decreased communication

Cell Bio 380 (3 decks)

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