Lesson 8 Cell Communication

Front 1

extracellular signal molecule

Back 1

a secreted or cell-surface molecule which, when bound to a receptor on a target cell, activates an intracellular signaling pathway

Front 2

signaling cell

Back 2

cell which secretes a signal molecule or displays one on its surface

Front 3

receptor protein

Back 3

proteins which initiate an intracellular signaling pathway when activated by an extracellular signal molecule

Front 4

intracellular signaling pathway

Back 4

series of linked reactions involving intracellular signaling proteins and mediators which ocurrs in response to receptor activation

Front 5

effector protein

Back 5

protein which, when activated, implements changes in the cell's behavior

Front 6

cell surface receptors

Back 6

transmembrane proteins which, when bound to signal molecules, initiate a cellular response

Front 7

contact dependent signaling

Back 7

signaling process involving the interaction between membrane-bound molecules on both signaling and target cells

Front 8

paracrine signaling

Back 8

signaling process carried out by local mediators which travel only short distances. Only target cells within a short distance of the signaling cell are affected

Front 9

autocrine signaling

Back 9

signaling process in which the signaling cell is the same as the target cell

Front 10

synaptic signaling

Back 10

signaling process involving the release of neurotransmitters from the signaling cell and binding of the neurotransmitters to receptors on a closely associated target cell

Front 11

endocrine signaling

Back 11

signaling process in which the signal molecules (hormones) are transported over great distances in the blood

Front 12

gap junctions

Back 12

aqueous channels which connect the cytosols of adjacent cells and allow for the exchange of small molecules

Front 13

morphogen

Back 13

signaling molecule involved in developmental processes which typically diffuses out from a localized soure to form a gradient

Front 14

nuclear receptors

Back 14

intracellular receptors which bind signal molecules capable of diffusing across a target cell's plasma membrane

Front 15

signal transducers

Back 15

aka surface receptors

Front 16

signal transduction

Back 16

conversion of a signal from one form to another such as the conversion of an extracellular signal to an intracellular one

Front 17

G-protein-coupled receptors GPCRs

Back 17

surface receptors which use trimeric GTP-binding proteins (G proteins) to convert ligand binding into an intracellular signal

Front 18

ion-channel coupled receptors

Back 18

receptors which are also ion channels. Binding of signal molecules to these receptors triggers the opening or closing of the ion channel

Front 19

enzyme coupled receptors

Back 19

receptors which have enzymatice activity or are directly associated with enzymes. Binding of signal molecules to these receptors activate the enzymatic activity.

Front 20

G protein

Back 20

a trimeric GTP-ginding protein with GRPase activity that couples GPCRs to membrane associated enzymes or ion channels

Front 21

small intracellular mediators

Back 21

small diffusible intracellular molecules, generated in respionse to receptor activation, which help to relay the signal to the interior of the cell

Front 22

intracellular signaling proteins

Back 22

large intracellular molecules which, in response to activation of a cell surface receptor, relay signals throughout the cell by either activating the next signaling molecule, generating small intracellular mediators or activating an effector protein

Front 23

scaffold proteins

Back 23

proteins which bind to groups of interacting intracellular signaling molecules and organize them into signaling complexes

Front 24

signalling cascade

Back 24

sequence of linked intracellular reactions usually involved in multiple amplification steps triggered by an activated cell-surface receptor

Front 25

molecular switches

Back 25

an intracellular signaling molecule which switches between on and off states

Front 26

small monomeric GTPases

Back 26

small GTP-binding proteins which have intrinsic GTPase activity and act as molecular switches

Front 27

GTPase activating proteins

Back 27

proteins which regulate GTP-binding proteins by increasing the rate of hydrolysis

Front 28

GEF factors

Back 28

proteins which regulate GTP-binding proteins by promoting the exchange of GTP to GDP

Front 29

Regulator of G protein signaling RGS

Back 29

g protein regulators, which are alpha subunit specific and activate G-protein by increasing the rate of GTP hydrolysis

Front 30

Receptor inactivation

Back 30

target cell desensitation due to a mechanism that causes a receptor to be non-responsive or unable to bind a ligand

Front 31

Receptor sequestration

Back 31

target cell desensitazation due to the temporary removal of a receptor from the cell surface by endocytosis making it unavailable for ligand binding

Front 32

receptor down regulation

Back 32

target cell desensitation due to the endocytosis and destruction of a receptor in lysosomes

Front 33

Negative feedback loop

Back 33

control mechanism whereby a product of a signaling response inhibits its own production

Front 34

positive feedback loop

Back 34

control mechanism where by a product of a signaling response acts to stimulate its own production

Front 35

desensitation/adaption

Back 35

a decrease in a cell's response level of a stimulus due to a prolonged exposure to the stimulus

Front 36

Adenylyl cyclase

Back 36

enzyme which catalyzes the conversion of ATP to cAMP

Front 37

Cyclic AMP phosphodiesterase

Back 37

enzyme which catalyzes the hydrolyses of cAMP

Front 38

cAMP dependent kinase PKA

Back 38

enzyme that phosphorylates serines and threonines on target proteins in response to a rise in intracellular cAMP

Front 39

CRE-binding protein CREB

Back 39

a gene regulatory protein activated by PKA phosphorylation

Front 40

Phospholipase C- ?
PLC

Back 40

enzyme actived by a G protein (Gq) which cleaves phosphatidylositol 4,5 bisphosphate into inositol 1,4,5 triphosphate (IP3) and diacylglycerol

Front 41

IP3-gated Ca2+ release channels (IP3 receptors)

Back 41

Ca2+ ion channels present in ER membranes which open in response to IP3 binding

Front 42

calmodulin

Back 42

A Ca2+ binding protein which is activated in response to increased cytosolic Ca2+ and helps relay Ca2+ signals by binding and activating other intracellular proteins

Front 43

Olfactory receptors

Back 43

GPCRs located on long cilia projecting from olfactory neurons

Front 44

Odorants

Back 44

signaling molecules which bind to receptors on olfactory neurons and trigger the sense of smell

Front 45

Olfactory neurons

Back 45

sensory nerve cells of the olfactory epithelium

Front 46

cAMP

Back 46

a small intracellular mediator formed from ATP by the action of adenylyl cyclase

Front 47

photoreceptor cells

Back 47

light sensitive cells to the retina

Front 48

rhodopsin

Back 48

light activated GPCR located in membrane discs of the outer segment of retinal photoreceptor cells

Front 49

cGMP

Back 49

a small intracellular mediator formed from GTP by the action of guanylyl cyclase

Front 50

Guanylyl Cyclase

Back 50

enzyme which catalyzes the conversion of GTP to cGMP

Front 51

cGMP phosphodiesterase

Back 51

enzyme which catalyzes the hydrolysis of cGMP

Front 52

Transducin

Back 52

G-protein associated with GPCR rhodopsin in photoreceptor cells

Front 53

Arrestins

Back 53

family of proteins which bind to phosphorylated GPCRs and participate their desensitation

Front 54

GPCR kinases
(GRKs)

Back 54

kinases which phosphorylate ligand bound GCPR and participate in their desensitation

Front 55

receptor tyrosine kinase

Back 55

enzyme couple receptor which, when activated by ligand binding, phosphorylates specific self tyrosines and tyrosines on a small number of intracellular signaling proteins

Front 56

tyrosine kinase associated receptors

Back 56

enzyme coupled receptors which have no enzymatic activity of their own but instead recruit cytoplasmic tyrosine kinases to relay a signal

Front 57

receptor serine/threonine kinase

Back 57

enzyme coupled receptors which phosphorylate specific self theonine/serine and theonine/serine of latent gene regulatory proteins

Front 58

SH2 domains

Back 58

highly conserved phosphotyrosine -binding domains

Front 59

PTB domains

Back 59

highly conserved phosphotyrosine -binding domains

Front 60

SH3 domains

Back 60

highly conserved proline rich binding domains

Front 61

Ras

Back 61

a small membrane bound GTPase often required for the stimulation of cell proliferation and differentiation

Front 62

MAP kinase signaling module

Back 62

An intracellular signal pathway composed of three kinases: MAPK, MAPKK, MAPKKK

Front 63

JAK-STAT signaling pathway

Back 63

one of the most direct signaling pathways from cell surface receptors to gene regulation in which tyrosine kinases (JAKs) phosphorylate gene regulatory proteins (STATs)

Front 64

Smad

Back 64

latent gene regulatory protein that is phosphorylated and activated by receptor serine/threonine kinases

Front 65

Protein kinase

Back 65

enzyme that transfers a phosphate group to a specific amino acid of a target protein

Front 66

Inositol 1,4,5 trisphosphate (IP3)

Back 66

small intracellular mediator, released from a plasma membrane phospholipid which binds to dand opens Ca2+ release channels in the ER

Front 67

Protein Kinase C (PKC)

Back 67

a Ca2+ dependent protein kinase that is activated by diacylglycerol

Front 68

Ca2+/calmodulin dependent kinase (CaM-kinase)

Back 68

protein kinase whose activity is regulated by the binding of Ca2+ activated calmodulin and which indirectly mediates the effects of Ca2+ by phosphorylation of target

Front 69

Phosphoinositide-3-kinase (PI 3-kinase)

Back 69

a kinase that phosphorylates inositol phospholipids at the 3 position of the inositol ring

Front 70

PH domains

Back 70

protein domain found in intracellular signaling proteins by which they bind to inositol phospholipids phosphorylated by PI 3-kinase

Front 71

T/F
GCPR act as GTPase activating proteins on the á subunits of G proteins.

Back 71

F

Front 72

General term for a signal relay chain containing multiple amplification steps

Back 72

Signal cascade

Front 73

One of the most direct signaling pathways from cell-surface receptors to gene regulation in which tyrosine kinases phosphorylate gene regulatory proteins

Back 73

JAK-STAT

Front 74

Protein domain found in intracellular signaling proteins by which they bind to inositol phospholipids phosphorylated by PI 3-kinase.

Back 74

PH domains

Front 75

Protein which binds to a GTP-binding protein and activates it by stimulating release of a bound GDP, thereby allowing it to bind GTP.

Back 75

GEF

Front 76

TF
Synaptic signaling and endocrine signaling are both capable of transmitting signals over a long distance

Back 76

True

Front 77

TF
Adenylyl cyclase is an enzyme which converts GTP to cGMP.

Back 77

False

Front 78

TF
In contrast to the more direct signaling pathways used by nuclear receptors, catalytic cascades of intracellular mediators provide numerous opportunities for amplifying the response to extracellular signals.

Back 78

True

Front 79

TF
Ras is an example of a signaling molecule which acts as a molecular switch.

Back 79

True

Front 80

TF
Identical cells are capable of responding in different ways when stimulated by different concentrations of the same signaling molecule.

Back 80

True

Front 81

A kinase that is involved in intracellular signaling pathways activated by cell surface receptors and that phosphorylates inositol phospholipids at the 3 position of the inositol ring.

Back 81

PI 3-kinase

Front 82

TF
A receptor which has been endocytosed will always be transported to lysosomes for destruction.

Back 82

False

Front 83

TF
The activity of any protein regulated by phosphorylation depends on the balance at any instant between the activities of the kinases that phosphorylate it and the phosphatases that dephosphorylate it.

Back 83

True

Front 84

Complex vesicle with invaginating buds and internal vesicles involved in the maturation of early endosomes into late endosomes.

Back 84

multivesicular bodies

Front 85

O-linked glycosylation occurs in what organelle?

Back 85

golgi apparatus

Front 86

Pathway for exocytosis that operates continuously in all cells.

Back 86

contituitive secretory pathway

Front 87

The coated vesicle that transports material from the plasma membrane, and between endosomal and Golgi compartments.

Back 87

Clathrin-coated vesicle

Front 88

TF
The release of histamine from mast cells is an example of regulated secretion

Back 88

True

Front 89

TF
All the molecules that enter early endosomes ultimately reach late endosomes

Back 89

False

Front 90

TF
The uptake of cholesterol (within low-density lipoproteins) by cells is an example of receptor-mediated endocytosis.

Back 90

True

Front 91

TF
Each cisternae of the Golgi apparatus contains the same set of processing enzymes

Back 91

False

Front 92

TF
Once a secretory vesicle is properly positioned beneath the plasma membrane, it will immediately fuse with the membrane and release its contents to the cell exterior.

Back 92

False

Front 93

Specialized class of small secretory vesicles that store neurotransmitter molecules.

Back 93

synaptic vesicles

Front 94

Cytosolic GTPase that binds to the neck of a clathrin-coated vesicle and helps it to pinch off from the membrane.

Back 94

Dynamin

Front 95

Side of the Golgi stack at which material enters the organelle

Back 95

Cis

Front 96

Lysosomal hydrolases delivered to early endodomes are inactive and require cleavage of an N-terminal domain for activation

Back 96

True

Front 97

TF
M6P groups are added exclusively to the N-linked oligosaccharides of soluble lysosomal enzymes as they are processed in the ER.

Back 97

False

Front 98

TF
In all events involving fusion of a vesicle to a target membrane, the cytosolic leaflets of the vesicle and target bilayers always fuse together, as do the leaflets that are not in contact with the cytosol.

Back 98

True