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Signal Transduction
information for exam 1
30
Biochemistry
Graduate
09/04/2011

Additional Biochemistry Flashcards

 


 

Cards

Term
Where do cells recieve signals form the environment beyond the plasma membrane
Definition
antigens, hormones, nuerotransmitters, touch
Term
Features of Signal-Transducing Systems
Definition

1. Specificity

2. amplification

3. desensitization/adaption ( receptor activation triggers a feedback that shut off the receptor or removes it from the cell)

4. integration (2 opposite charges)

Term

where do the link up with

g-protien

enzyme

ligan-gated ion channels

other membrance recptors

nuclear receptors

 

Definition

epinephrine (receptor)

insulin

lnicotinic acetylcholine

integrin

sterile

Term
Receptor
Definition
A membrane-bound or soluble protein or protein
complex, which exerts a physiological effect (intrinsic effect),
after binding its natural ligand.
Term
Six General Types of Signal Transducers
Definition

G-protein-coupled receptor

receptor tyrosine kinase

receptor guanylyl cyclase

adhesion receptos (integrin)

Gated ion channel

nuclear recptor

Term
G-protein-coupled receptor
Definition

external ligand (S) binding to receptor (R) activate an intracellular GTP-binding protein (G), which regulates an enzyme (ENZ) that generates an intracellular second messanger, X

 

50% of all drugs on the market target GPCR

Term

Receptor tyrosine kinase

 

Definition
ligand binding activates tyrosine kinase activity by autophosphorylation
Term
Receptor guanylyl cyclase
Definition
ligand binding to extracellular domain stimulates formation of second messanger cAMP
Term
adhesion receptor
Definition
binds molecules in extracellular matrix, changes conformation, thus altering its interaction with cytoskeleton
Term
gated-ion channel
Definition
opens or closes in response to concentration of signal ligand or membrane potential
Term
nuclear receptor
Definition
steriod binding allows the receptor to regulate the expression of specific genes
Term

G-protein coupled receptor

-beta-adrenergic receptor which mediates the effect of epinephrine is the target of ________

-beta-adrenergic receptor acts through the second messanger____

Definition

-beta blockers

 

-cAMP

Term

propanolol

 

Definition

beta blocker, for hypertension (HT), antagonist of epinenphrine cascade.

 

off labeled kinds: tremors, stage fright

Term
isopoterenol
Definition
beta agonist, low blood pressure, from shock, heart attack, asthma attack (beta 2)
Term
three essential components of G-protein coupled receptors (GPCP)
Definition
-Plasma membrane receptor with seven
transmembrane helical segments
–Effector enzyme in the plasma membrane that
generates an intracellular 2nd messenger
–Guanosine nucleotide binding protein (G protein)
that activates the effector enzyme
Term
beta adregenic pathway (7 steps)
Definition

1. epinephrine binds to specific receptor

2. occupied receptor cause replacement of the GDP bound to G(s) by GTP, activates G(s)

3. G(s) (alpha subunit) moves to adrenayl cyclase and activates it

4. adrenayl cyclase catalyzes formation of cAMP

(can go to ways)

first is: 5.cAMP activates PKA

6. phosphorylation of cellular protein by PKA causes cellular response to epinenphrine

 

second way: 7. cAMP is degraded, reversed activation of PKA

 

Term
Some signals that use cAMP as second messenger
Definition
Glucagon, histamine, serotonin, somatostatin
Term

Enzyme-linked Membrane Receptors

Many membrane receptors consists of  _____ and of____                               
-The most common catalytic domains have

Definition

extracellular binding domain and of intracellular catalytic domain

 

-tyrosine kinase activity (add phosphate group to itself; auto-phosphorylation)

Term

Epidermal growth factor receptor (EGFR)

Cell surface receptor for members of the ___ family of extracellular ______

Definition
EGF, protein ligands
Term

Epidermal Growth Factor Receptor (EGFR)

-Mutations affecting EGFR expression or activity may result in ______

Definition

cancer

 

Term

Epidermal Growth Factor Receptor (EGFR)

1. Exists in its ______

2. activated by binding of its _____ (two big ones are EGF and TGF alpha)

3. transition to ______

Definition

1. inactive monomers

2. specific ligand

3. active form (homodiner)

Term

t

Therapies

 

Definition

Tyrosine kinase inhibitors                                                         Colorectal cancer, non small cell lung cancer, squamous cell carcinoma of head and neck

 

Monoclonal

Term

Monoclonal Antibodies

bind to the EC of EGFR, _______


Cetuximab

 

 

Definition

prevents ligand binding

 

iv injection

colorectal, head and neck cancers

30,000 for 8 weeks

combination therapy with chemotherapy

Term

Tyrosine Kinase Inhibitors

bind to IC domain of EGFR, _______

 

Gefitinib (Iressa)

selective inhibitor of EGFR tyrosine kinase domain, binds to the _______

Definition

prevents phosphorylation


ATP binding spot

advanced or metastic non small lung cancer

infrequent side affects

may be replaced by erlotinib (efficacy)

$1575 per 21 day supply (average of 5 months of treatment)

Term

Nuclear receptor

 

-tamoxifan

Definition

steriod hormones

act in the nucleus to alter gene expression

 

-used for estrogen dependent breast cancer

cell division depends on presence of estrogen

tamoxifan is an antagonist

Term
Avenues for COmbination Therapy
Definition

-Dual Inhibition of EGFR Signaling Using the
Combination of Cetuximab and Erlotinib
• Clinical trial started October 2008
–Cetuximab 400mg/2X per week
–Erlotinib 100mg daily

 

used for when all other treatments have failed (life expectancy is 6 months)

Term
other tryosine kinase inhibitors (dasatinib)
Definition

Dasatinib:

for luekemia

oral

downside are the side effects (nausea,stomach, fever, etc). Not bad side effects just a lot of them

lots of drug interaction

Term
Cell division cycle
Definition

takes 24 hours

 

interphase: G1, sythensis (S), G2

 

cell division: Mitosis (M)

Term
Cancer cells
Definition

grow fast

best target is in M phase

if bad cell hits a good cell, then good cell dies

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