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Physiology Test 1 > 3 4 5 Cell Signaling > Flashcards

3 4 5 Cell Signaling Flashcards

1
Q

gap jxn transmit ___ signals

A

electrical

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2
Q

gap jxn 1/ link and 2/ fxns include

A

1/ cytoplasm of two neighboring cells
2/ rapid txmission of APs, diffusion of metabolites ( eg ATP) and second messengers (eg Ca2+)

heart, brain cells

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3
Q

membrane bound signaling molecules

A

like gap jxns but farther apart
contact-dependent - cells next to ea other
signaling molecule bound to PM of one cell and interacts directly with receptor of adjacent target cell

immune cells

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4
Q

communication by chemical signals - main steps

A 
*major form of xfer of info*
multi-layered transduction process
release of signal by signaling cell
transfer of signal
detection by receptor
decoding of signal by target cell
activation of effector molecule
response
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5
Q

neurocrine signals

A

neurotransmitters
i.e. noradrenaline, acetylcholine
released from nerve terminals into synaptic cleft to communicate with other neurons or non-neurons

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6
Q

endocrine signals

A

hormones
i.e. adrenaline, insulin, steroids
made and released from endocrine cells
transported to blood to target organ/cell

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7
Q

paracrine signals

A

i.e. histamine

made and released from endocrine cells, travel very short distances to target organ/cell

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8
Q

autocrine signals

A

i.e. prostaglandins

signaling and target cell is the same (itself)

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9
Q

hydrophobic signals

A

i.e. steroid hormones
diffused through membrane

activate nuclear transcription pathways (genomic pathway) via intracellular receptors

initiation of GENE TRANSCRIPTION!

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10
Q

hydrophilic signals

A

i.e. most signals
cell impermeable
recognized by plasma membrane receptors

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11
Q

PM receptors have 2 main fxns

A

1/ detect incoming signal

2/ transmit signal to cell interior

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12
Q

binding of ligand to receptors is (4)

A

of high affinity
saturable
reversible
specific

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13
Q

ligand-gated (ionotropic) receptors

A

ion channels
fastest of all receptors
binding of the ligand opens the channel to ions due to a conformational change

combines receptor, transducer, and amplifier

e.g. nicotinic receptors, GABA receptors

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14
Q

ligand-gated receptor functions (2)

A

1/ alter membrane potential to regulate excitable cells

2/ alter intracellular Ca2+ concentrations

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15
Q

g protein coupled receptors (GPCRs)

A

receptors coupled to heteroTRIMERIC g proteins (GDP or GTP) that fxn as transducers

7 transmembrane receptors

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16
Q

examples of GPCRs (2)

A

muscarinic receptors

adrenergic receptors

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17
Q

GPCRs are inactive when

A

g protein attached to GDP

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18
Q

GPCRs are active when

A

g protein attached to GTP

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19
Q

receptor tyrosine kinases

A

enzyme is intrinsic to receptor
single membrane spanning receptors
extracellular area binds the signal, causes dimerization of receptors and phosphorylation of receptor by intrinsic tyrosine kinase activity
cytosolic area has enzyme activity that tranduces signal

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20
Q

signal transduction by GPCRs requires 3 membrane bound proteins

A

1/ receptor
2/ G protein
3/ amplifier

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21
Q

N terminus of the GPCR

A

ligand binding domain

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22
Q

C terminus of the GPCR

A

exposed to cytosol

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23
Q

GPCR stimuli (long list)

A 
light
odors
tastes
ions
amino acids
amines
nucleotides
nucleosides
prostaglandins
lipids
peptides
proteins
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24
Q

when a GPCR is activated, this happens

A

GDP-a is released in exchange for GTP
a subunit detaches from B-gamma and attaches to GTP
so you are left with GTP-a and B-gamma

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25
Q

these 2 components of a GPCR can generate second messenger dependent cellular responses

A

GTP-a

Beta-gamma

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26
Q

active GTP-a is deactivated by

A

hydrolysis of GTP via GTPase that is intrinsic to the a subunit

leads to GDP-a + B-gamma (trimer formation)

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27
Q

4 types of G proteins

A

Gs
Gi
G1
G12

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28
Q

Gs amplifier

A 
adenylyl cyclases (AC)
stimulation
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29
Q

Gs amplifier

A

adenylyl cyclases (AC)
stimulation
B1 and B2

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30
Q

Gi amplifier

A

adenylyl cyclases (AC)
inhibition
a2

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31
Q

Gq amplifier

A

PLC-B
stimulation
a1

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32
Q

acetylcholine has two types of receptors

A

nicotinic

muscarinic

33
Q

acetylcholine ligand-gated receptor

A

nicotinic receptor

34
Q

acetylcholine GPCR

A

muscarnic receptor

35
Q

main second messengers (5)

A 
cAMP
cGMP
IP3
DAG
Ca2+
36
Q

second messenger AC/cAMP pathway

A

AC = membrane bound
activation generates cAMP from ATP
activated by Gs-a (GTP bound)
inhibited by Gi-a or Go-a (GTP bound)

37
Q

Gs - AC increased - ____ second messenger

A

cAMP increased

38
Q

Gi - AC decreased - ____ second messenger

A

cAMP decreased

39
Q

Gq - PLC-B increased - ____ second messenger

A

IP3, DAG

40
Q

Gq - PLC-B increased - ____ second messenger

A

IP3/Ca2+, DAG

41
Q

hydrolysis of PIP2 by PLC leads to

A

DAG and IP3

42
Q

PLC-gamma is activated by

A

tyrosine phosphorylated receptor kinases

43
Q

upon hydrolysis of PIP2, DAG stays in the membrane and IP3 diffuses to the endo/SR to release _____

A

Ca2+

via binding to IP3 receptors

44
Q

main fxn of DAG (result of second messenger PIP2) is to

A

activate protein kinase C

45
Q

Ca2+ “on” mechanisms consist of (2 things)

A

1/ Ca2+ entry across plasma membrane

2/ Ca2+ release from intracellular stores

46
Q

Ca2+ entry across PM is carried out by (2 things)

A

voltage gated channels

ligand gated channels

47
Q

Ca2+ release from intracellular stores is carried out by (2 things)

A

IP3 receptors

ryanodine receptors

48
Q

activation of CG results in generation of second messenger _____

A

cGMP from GTP

49
Q

guanylyl cyclases are associated with (2 things)

A

membrane/particulate GC

cytosol/soluble GC

50
Q

physiological activator of particulate GC (guanylyl cyclase)

A

natriuretic peptides

51
Q

physiological activator of soluble GC (guanylyl cyclase)

A

nitric oxide (NO)

52
Q

RGS proteins

A

regulators of g-protein signaling

terminate g-protein signaling

53
Q

RGS proteins

A

“regulators of g-protein signaling”
they terminate g-protein signaling
they are GTPase activating (GAP), promoting GTP hydrolysis

54
Q

termination of cAMP/cGMP signaling is done by

A

PDEs (phosphodiesterases)

55
Q

cAMP is turned into 5’AMP by

A

PDE4

PDE1

56
Q

cGMP is turned into 5’GMP by

A

PDE5

PDE1

57
Q

small G proteins

A

monomeric G proteins

i.e. Ras and Rho

58
Q

small G proteins are activated by

A

GPT exchange factors (GEFs)

59
Q

small G proteins are turned off by

A

GAPs: GTPase activating factors

60
Q

___ phosphorylate proteins

A

kinases

61
Q

____de-phosphorylate proteins

A

phosphatases

62
Q

these three amino acids participate in protein phosphorylation

A

serine
threonine
tyrosine

63
Q

cAMP-dependent protein kinase (PKA)

A

serine/threonine kinase

inactive as a tetramer (2 regulatory subunits, 2 catalytic subunits)

64
Q

____ binds to regulatory units of PKA to activate it

A

cAMP (2 cAMP molecules per regulatory subunit, so 4 cAMP molecules total)

65
Q

(5) serine/threonine kinases

A

PKA: cAMP dependent protein kinase
PKG: cGMP dependent protein kinase
PKC: protein kinase C
caMK: Ca2+/calmodulin dependent protein kinase
MAPK/ERK: mitogen-activated protein kinase/extracellular signal related kinase

66
Q

MAPKs

A

growth factors activate them
activated by phosphorylation of an upstream kinase
leads to activation of transcription factors

67
Q

amplification

A

receptor–> G protein –> second messenger –> kinase –> phosphorylation

68
Q

receptor tyrosine kinase

A

growth factor receptor

monomer, gets activated by dimerization

69
Q

phosphorylation of receptor tyrosine kinases provides docking sites for a number of proteins containing SH2 domain or PTB domain, including ___ and ____

A

Grb2

PLC-gamma

70
Q

___ attaches to Grb2

A

Sos protein (a GEF, activator of small G protein Ras)

71
Q

___ activates Ras

A

Sos

72
Q

activation of PLC-gamma and hydrolysis of PIP2 leads to

A

second messengers IP3 and DAG

73
Q

Activation of PI3 kinase results in formation of ___

A

PIP3

74
Q

RTKs have 2 jobs

A

1/ receptor (tyrosine kinase activity)

2/ recruitment of other molecules

75
Q

this hormone is also a receptor tyrosine kinase

A

insulin

76
Q

insulin receptor activates the

A

PI3K pathway via IRS (Insulin Receptor Substrate)

77
Q

insulin receptor consists of

A

2 extracellular a chains and 2 transmembrane B chains (with intrinsic tyrosine kinase activity) connected by disulfide bonds

78
Q

tyrosine kinases include (2)

A

growth factor receptor

insulin receptor

79
Q

____ or ____ reverse phosphorylation

A

serine/threonine phosphatases or tyrosine phosphatases

Physiology Test 1 (8 decks)

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