signal transdcution

Question 1

What are MAP Kinases

Answer 1

serine/threonine kinases involved in regulation of many cell processes. (proliferation,apoptosi)

Question 2

which is the SH2 domain protein in map K

Answer 2

GRB- docks onto the tyrosine residues

Question 3

core kinase in Map K

Answer 3

Ras

Question 4

signalling molecule-MAP K

Answer 4

Growth factor e.g IGF 1 , EGF

Question 5

What is the function of SOS

Answer 5

Guanine nucleotide exchange factor for RAS

Question 6

what is the pathway of insulin?

Answer 6

Still tyrosine kinase but a special type

Question 7

Pathway of insulin

Answer 7

1. Insulin binds to alpha
2. Dimerises - the b subunits have kinase activity its heterotetrameric 2 a and 2 b which are transmembrane
3. Autophosphorylation
4. Phosphorylates IRS1
5. PI3K (phosphoinosittid 3 kinase)
6. Pip 2 - Pip 3 -PDK1 (enzyme)- AKT/protein kinase B. (enzyme)
7. AKT phosphorylates inhibitory proteinAS160 which usually prevent GLUT 4. Also phosphorylates GSK3 which is an inhibitor of glycogen synthase.

Question 8

The role of insulin in signal transduction

Answer 8

Has a mitogenic function (MAP K)

and also pathway is metabolic effect (PI3K)

Question 9

what kind of molecules are chemical messengers usually?

Answer 9

hydrophilic only 4 are hydrophobic

• steroid hormones
• active vitamins D and A
• Thyroid hormones

Question 10

what mechanism do the hormones produced by the hypothalamus work with

Answer 10

Phospholipase C

Question 11

relationship between PPP and Insulin

Answer 11

insulin activates PPP (anabolic)

Question 12

GLUT 4 tissues

Answer 12

adipose, muscle, heart

Question 13

GLUT 1

Answer 13

all cells, RBC - Insulin Independant

Question 14

GLUT 3

Answer 14

brain, neurons, sperm. function in (hypo)
insulin indwpendant
high affinity, low KM

Question 15

Explain MAP K

Answer 15

1. ligand binds
2. Dimerisation
3. Autophosphorlation
4. GRB 2 docks
5. SOS binds
6. RAS activated
7. Kinase reaction

Question 16

Glut 5

Answer 16

enterocytes of small intestine for the uptake of fructurse

Question 17

GLUT 2

Answer 17

pancreas, liver, small intestine - (HYPER) low affinity and high KM -insulin independant

Question 18

which pathway is associated with TYRK

Answer 18

JACK STAT- growth hormones

Question 19

what are the molecules trigger JACK STAT

Answer 19

prolactin, GH, cytokines, INF

Question 20

IL-6

Answer 20

pro inflammatory cytokine, associated with hepicidin which decreases iron levels by stopping ferroportin. Hepcidin increases when IL -6 is present. Hepcidin blocks fe release from liver and SI

Question 21

JACK STAT

Answer 21

• cytokines and GH
• intracellular part of receptor associated with Jack (janus kinase)
• signal binds and the jacks phosphorylate each other
• Jacks phosphorylate Tyr
• causes STAT (TF) to bind to the Tyr
• JACK phosphorylates STAT
• STAT dissociates from receptor goes to nucleus binds ta response elements and activates gene transcription

Question 22

Receptors with serine/threonine kinase activity

Answer 22

TGF -B receptors (transforming growth factors)

TGF receptor is complex, has 2 different receptor subunits. first 1 type 2 gets activated by the signalling molecule (TGF) then activates type 1 by phosphorylation at a ser residue.

type 1 binds to Smad (R-smad) which it phosphorylates at ser. R-smad dissociates from receptor and forms complex with co-smad. smad complex goes to nucleus to affect transcription.

Smads are gene specific TF’S

TGF is a hormone/cytokine involved in tissue repair, immune regulation , cell proliferation and bone morphogenic proteins (BMPS)

Question 23

what does associeted TYR kinase mean

Answer 23

The receptor itself has no intrinsic kinase activity but binds the the tyrosine kinase JACK

Question 24

Non receptor serine/threonine kinases

Answer 24

These are several serine/threonine protein kinases that are responsible for phosphorylating a variety of intracellular proteins on ser/thre residues. the most important are PK C A G

Question 25

mtor

Answer 25

ser/thr kinase regulates autophagy, proliferation, protein synthesis transcriptpm. coded for by FRAP 1 gene. forms 2 different complexes. rapamycin is a bacterial toxin that inhibits mtor by binding to its intracellular receptor FKBP12 mtor integrates the signal pathways of insulin, growth factors (iGF 1/2_

Question 26

PKG

Answer 26

directly stimulates 1. synthesis of nO 2. soluble intracellular Gunayl cyclase INHIBITS phosphodiesterasde 5 - which selectively cleaves cgmp PKG also modulates the PKG also modulates the intracellular concentration of intracellular concentration of Са2+, which is a key ion for activity of , which is a key ion for activity of ( eNOS) and nNOS

Question 27

NOS pathway

Answer 27

1. stimulate muscle with ACH 2. Ativates ca dependant NOS synthase 3. gas so diffuses to muscle and you have soluable guanyl cyclase there. binds to it, turns GTP-CGMP-PKC G 4. relaxation of smooth muscle by activation of myosin light chain phospahatse

Question 28

PTEN

Answer 28

is a phosphatase which dephospharataltes PIP 3 thus inhibiting the PI3K pathway. its acts as a tumour supressor gene.

Question 29

what is the signalling molecule for PI3K

Answer 29

insulin, growth factors like a PDGF,EGF

Question 30

natriuretic peptide and receptors

Answer 30

It relaeases NA in urine 3 receptors NPRA NPRB NPRAC- g protein linked and is a clearance receptor that internalises and destroys the ligand

Question 31

which is the aa precursor for nO

Answer 31

arginine

Question 32

plasma membrane receptors

Answer 32

1. associated with ion channels 2. associated with G proteins 3. with intracellular domains with enzymatic activity - tk activity - tyrosine phosphatase - serine/thr activity - gunaylate cyclase activity 4. death receptors 5. integrins

Question 33

G proteins

Answer 33

so called as they bind to guanine nucleotides heterotrimeric Receptor spans the membrane 7 times in its inactive state GS a has GDP bound when ligand binds causes a conformational change replacement. the a subunit and GTP dissociate to go and activate adenylate cyclase - ATP----CAMP---PKA - for response to stop GTP will be hydrolysed by GTPASE T then a will rejoin others.

Question 34

example of g protein

Answer 34

adrenaline

Question 35

different types of g proteins

Answer 35

1. GS a-increases camp 2. GI a- decreases camp 3. GQ- involved in the ip3 pathway s 4. Gt transducin

Question 36

g transducin

Answer 36

responsible for generating the signal int he rods of retina in response to light. it stimulates CGMP phosphodiesterase (break down)

Question 37

Regulation of glycogen synthase and phosphorylase

Answer 37

GS :) - Insulin :( glucagon and epinephrin GP :) glucagon and epinephrin :( insulin

Question 38

G protein that regulate ion channels

Answer 38

Muscarinic ACH receptor in the heart . linked to K channels when ACH binds stimulates the G inhibitory unit now b and gamma dissociate, bind to channels increasing k permeability, hyperpolarizing membrane and decreasing frequency of contractions

Question 39

rod cells

Answer 39

In dark, rod cells have a high level of cGMP which keeps the gates open (na)). When there is light activates opsin which cause sa displacement of gdp on a g protein called transdcucin. This activates Cgmp phosphodiesterase convertes CGMP-GMP leads to dissociation of cgmo from channeles leads them to close-----generate AP

Question 40

second messangers

Answer 40

They amplify the signal because more of it is produced compared to the first messenger. they are short lived intracellular signalling molecules. removal of the 2nd messenger terminates the response the communication between cells 1. Ca 2. No/co 3. CAMP/CGM[