Biochem Signal Transduction

Front 1

What are the 4 types of cell signaling?

Back 1

1) Endocrine
2) Paracrine
3) Neuronal
4) Contact dependent

Front 2

What is endocrine signaling?

Back 2

Endocrine cells form hormones, which are released into the blood to act on target cells throughout body.

Front 3

What are the three chemical groups of hormones?

Back 3

1) Steroid
2) Proteinaceous
3) Amino-acid related

Front 4

What is paracrine signaling?

Back 4

These molecules diffuse LOCALLY through EC medium, remaining in the neighborhood of the secreting cell.

Front 5

What are examples of paracrine signaling?

Back 5

-Growth factors
-Eicosanoids
-NO

Front 6

autocrine signaling

Back 6

cells respond to substances that they themselves release

Front 7

neuronal signaling

Back 7

neurotransmitters carry signals btwn neurons or from neurons to other target cells (synaptic binding)

Front 8

examples of neuronal signaling

Back 8

acetycholine, dopamine, norepinephrine

Front 9

contact-dependent

Back 9

no secretion, direct cell-cell or cell-matrix interactions

Front 10

Pharmacological example of eicosanoids?

Back 10

NSAIDS, inhibition of enzymes (prostaglandins and thrombaxanes) that make eicosonoids.

Front 11

Pharmacological example of Nitric Oxide?

Back 11

Nitroglycerin treats angina pectoris, and releases NO to relax blood vessels.

Front 12

Intracellular receptors

Back 12

signal molecule diffuses thru membrane to receptor (lipsoluble)

Front 13

types of intracellular receptors

Back 13

1) gene regulatory proteins
2) enzymes

Front 14

examples of intracellular receptors

Back 14

steroid hormones, vitamin D, thyroid hormones (receptors are TFs)

Front 15

cell-surface receptors

Back 15

proteins, peptides, and other hydrosolubles can't cross plasma membrane

Front 16

3 families of cell-surface receptors

Back 16

1) ion-channel linked receptors
2) g-protein linked receptors
3) enzyme-linked receptors

Front 17

ion-channel linked receptors

Back 17

transduce chem. signal into an elecrtrical sign., changes in voltage across plasma membrane

Front 18

G Protein-linked receptors

Back 18

form largest fam. of cell surface receptors, mediate responses to hormones, local mediators, neurotransmitters

Front 19

3 Components of G Protein-linked receptors

Back 19

1) Cell-surface receptor
2) G protein
3) effector: an enzyme or ion channel

Front 20

G protein

Back 20

single polypeptide spans membrane 7x, "alpha, beta, gamma"

Front 21

Gs

Back 21

-activates adenylyl cyclase
-(as,b, g)

Front 22

Gi

Back 22

-inhibits adenylyl cyclase
-regulates ion channels
-ai, b, g

Front 23

Gq

Back 23

-activates phospholipase C
-aq, b, g

Front 24

Gt

Back 24

-transducin activated cGMP
-at,b, g

Front 25

How does G protein work

Back 25

-alpha until has GDP
-hormone binds= conformation change
-x/c GDP for GTP
-alpha/beta can diffuse membrane

Front 26

targets of G Protein subunits

Back 26

1) Ion channels
2) membrane bound enzymes

Front 27

Ion channels

Back 27

HR controlled by 2 sets of nerve fibers:
1) fires to speed up heart
2) fires to slow it down

Front 28

Membrane bound enzymes

Back 28

more complex
-further intracellular signalling moelcules (2nd messengers)

Front 29

Adenylyl cyclase

Back 29

-target enzyme for G protein
-catalyzes formation of cAMP

Front 30

Phospholipase C

Back 30

-target enzyme for G protein
-catalyzes formation of IP3 & DAG

Front 31

Example of pharmacological G protein

Back 31

-B adrenergic receptors (epinephrine) activate adenylyl cyclase
-causes relaxation/ bronchodilation

Front 32

Signal amplification

Back 32

1) ea. mol. epinephrine activates 1 receptor
2) 1 receptor activates many Gs
3) ea. Gs activates adenylyl cyclase
4) synthesizes many cAMPS
5) ea. protein kinase A phosphorylates phos. kinase
6) so on

Front 33

How is adenylyl cyclase turned off?

Back 33

-GTP=GDP
-as-GDP dissociates
-Adenylyl cyclase deacts.
-as-GDP goes back to B subunit to form inactive Gs

Front 34

Cholera toxin

Back 34

-modifies alpha of Gs
-no GTP
-therefore Gs continually activated adenylyl cyclase
-massive Cl-, H20, Na=diarrhea dehydration

Front 35

Ca triggers

Back 35

-free Ca binds to calmodulin= enables complex to regulate
-phosphorylase kinase=glycogen breakdown

Front 36

Kd

Back 36

equilibrium dissociation constant
-if decrease, affinity increases

Front 37

fractional occupancy

Back 37

fraction of all receptors occupied by hormone
[Rt]=[R]+[HR]