Cell Signaling

Question 1

What are the steps of cell signaling

Answer 1

Hydrophillic signals attach to then make it active cell surface receptor
The signal then moves to transduction protiens and second messengers
This signal then goes to an effector protien

Question 2

What can an effector protien do

Answer 2

Modify cellular metabolism, function, movement or go into the nucleus that then effects gene expression, development

Question 3

What are the four forms of intercellular signaling

Answer 3

Endocrine signalling (blood vessel)
Autocrine
Paracrine signalling
Signalling by plasma membrane-attached proteins

Question 4

What is autocrine signaling

Answer 4

Targets sites on same cell

Question 5

What is paracrine signaling

Answer 5

When one cell secrets a chemical affecting neighboring cells

Question 6

What is endocrine signaling

Answer 6

Process by which hormones are reeleased from the endocrine glands and diffuse through the blood

Question 7

Can signaling molecules act in both endocrine and paracrine signaling

Answer 7

YES in epinephrine

Question 8

What is a nuclear superfamily

What is in the cytoplasm and what is in the nucleus

Answer 8

Inter cellular and can cause an effect in the nucleus usally is composed of a family of transcrption factors they have highly conserved DNA binding regions and ligand binding regions

Cytoplasm- Estrogen, Progesterone and Glucocrticoid
Nucleus- Thyroxine and retinoic acid

Question 9

How does the glucocorticoid receptor work

Answer 9

It is on the DBD and there is an inhibitor which is HSP90 on the LBD when the hormone comes it it removes the inhibitor and now it can bind to certain promoter sequences

Question 10

How does the receptor get into the nucleus from the cytosol

Answer 10

It is hydrophobic so it can cross the membrane

Question 11

What is the basic pathway of transduction

Answer 11

• You have an extracellular signal molecule that binds to the ligand
• Then you have a cytoplasmic portion
• It then goes to the intracelllular signaling protiens or molecules
• This will then effect effector protiens

Question 12

What is considered the primary messengar in signal transduction

Answer 12

THe extracellular signal molecule

Question 13

What are some examples of effector protiens and what do they effect

There 3

Answer 13

Metabolic enzyme- alterd metabolism
Gene regulatory- altered gene expression
Cytoskeletal protien- altered cell shape or movement

Question 14

What are the steps in signaling by cell surface receptors

Answer 14

1. Synthesis and release the signaling molecule by the singlaing cell
2. transport and binding the signal to a specefic receptor of the target cell which result5.s in change of confirmation
3. Initation one or more intracellular signal-transduction pathways
4. Short term cellular response
5. Long-term cellular responses
6. Termination of cellular response

Question 15

What are some examples of fast cellular pathway

Answer 15

Changes in ion transport, cell movement, secretion or metabolism

Question 16

What are some slower pathways

Answer 16

Gene regulated changes in cell growth and divison

Question 17

What are the 4 extracellular signal molecules

Answer 17

1. Survival signals
2. Growth and divide
3. Differentiatie
4. Die

Question 18

What are the two signals of aptosis

Answer 18

1. Removal of survival factors
2. Death signals

Question 19

What is binding speceficity based on

Answer 19

Molecular complementarity between the interacting surfaces of receptor and and ligand (non covalent forces)
Along with having corresponding charges

Question 20

What can signaling molecules also do

Answer 20

Signaling molecules or ligans can induce receptor dimerixation where an additional receptor comes in

Question 21

What is the disocation constant

Answer 21

Kd= (R)(L)/(RL)

Question 22

How do you get R and L

Answer 22

adding them together

Question 23

What is kd the measure of

Answer 23

Affintiy of a receptor to its ligand it is the ligand concetration that is required to bind 50% of the cell surface receptrors

Question 24

What does a smaller Kd mean

Answer 24

The lower the ligand concentration required to occupy 50% of the cell surfac receptors

Question 25

How can you tell what sequence is expressing for a certain receptor for a ligand

Answer 25

You take a cell that has that has that receptor and then you Insert the cell with cDNA library and screen for cellular phenotype associated with that ligand Identify the incorporated cDNA by PCR followed by sequencing The receptor protein can be deduced from the cDNA sequence Can then mutate specific amino acids to determine essential ligand binding domain

Question 26

What are the three type of kinases

Answer 26

1. Tyrosine Kinases 2. Serine/Threonine Kinases 3. Dual Kinases which cna do all three

Question 27

What are the three types of phosphatases

Answer 27

1. Tyrosine Phosphatases 2. Serine/Theronine Phosphatases 3. Dual Phosphatases

Question 28

What do kinases and phosphatases do

Answer 28

Kinase puts on phosphates Phosphatases removes phosphate groups

Question 29

What can you tell from phospho-specefic antiobodies

Answer 29

They can reveal activation of signal transduction pathways the more you have phosphates from (kinase) it will create an increase in production of the protien

Question 30

What are the forms that G protien exist in

Answer 30

1. Active-bound to GTP 2. Inactive-bound to GDP

Question 31

How do you go from inactive to active form

Answer 31

You have to be able to remove the GDP form you can do this by using GEF which is an activator protien that replaces GDP with GTP

Question 32

How do you go from the active form to an inactive form

Answer 32

You have to hydrolyze the GTP and you can do this with the help of GAP which is a GTPase

Question 33

Are the gates opened in the active state

Answer 33

No they are opened in the off state

Question 34

How many domains are in a protein coupled receptors

Answer 34

7

Question 35

What are the three subunits of the G-protien complex

Answer 35

Ga Gb and Gg

Question 36

What protiens are lipid anchor in the G complex

Answer 36

Ga and Gg

Question 37

What are the steps ot activate GPCR

Answer 37

You have agonist binding to an inactive receptor The G protien in inactive because it is bound to GDP When the receptor is active it will bind to the alpha unit Dissociaton of GTP to GDP occurs The alpha unit then dissocates from the B and Y sub unit The GTP complex with the alpha unit attach to an effector protien Hydrolsis of GTP alllows the alpha to go and rejoin the Gb and Gg and it restarts

Question 38

What happens when to the B and Y sub unit when the alpha dissocates

Answer 38

Can sometimes bind to an ion channel and it usually is going to open an ion channel but this can be a rare event

Question 39

What is CAMP

Answer 39

acts as an extracellular signalling molecule that can binds to and signals via a G protein coupled receptor

Question 40

How cna you demonstrate how a receptor mediated dissociation of Ga and GBG using FRET

Answer 40

The Ga of the comples is bound to the CFP protien and GB fuses with YFP When they are close together in other words are not dissociated they release the yellow light But when it switches to GTP form where the ligand binding leads to dissociation no more ressoance energy

Question 41

What would the line graph look like between cAMP being added and the ammount of yellow light

Answer 41

At first there would be a high amount of yellow light an then has time progressed and more ligand became bound it decrease in the ammount of light