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Physiology Test 1 > 3 4 5 Cell Signaling > Flashcards

3 4 5 Cell Signaling Flashcards

(79 cards)

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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
these 2 components of a GPCR can generate second messenger dependent cellular responses
GTP-a | Beta-gamma
26
active GTP-a is deactivated by
hydrolysis of GTP via GTPase that is intrinsic to the a subunit leads to GDP-a + B-gamma (trimer formation)
27
4 types of G proteins
Gs Gi G1 G12
28
Gs amplifier
``` adenylyl cyclases (AC) stimulation ```
29
Gs amplifier
adenylyl cyclases (AC) stimulation B1 and B2
30
Gi amplifier
adenylyl cyclases (AC) inhibition a2
31
Gq amplifier
PLC-B stimulation a1
32
acetylcholine has two types of receptors
nicotinic | muscarinic
33
acetylcholine ligand-gated receptor
nicotinic receptor
34
acetylcholine GPCR
muscarnic receptor
35
main second messengers (5)
``` cAMP cGMP IP3 DAG Ca2+ ```
36
second messenger AC/cAMP pathway
AC = membrane bound activation generates cAMP from ATP activated by Gs-a (GTP bound) inhibited by Gi-a or Go-a (GTP bound)
37
Gs - AC increased - ____ second messenger
cAMP increased
38
Gi - AC decreased - ____ second messenger
cAMP decreased
39
Gq - PLC-B increased - ____ second messenger
IP3, DAG
40
Gq - PLC-B increased - ____ second messenger
IP3/Ca2+, DAG
41
hydrolysis of PIP2 by PLC leads to
DAG and IP3
42
PLC-gamma is activated by
tyrosine phosphorylated receptor kinases
43
upon hydrolysis of PIP2, DAG stays in the membrane and IP3 diffuses to the endo/SR to release _____
Ca2+ | via binding to IP3 receptors
44
main fxn of DAG (result of second messenger PIP2) is to
activate protein kinase C
45
Ca2+ "on" mechanisms consist of (2 things)
1/ Ca2+ entry across plasma membrane | 2/ Ca2+ release from intracellular stores
46
Ca2+ entry across PM is carried out by (2 things)
voltage gated channels | ligand gated channels
47
Ca2+ release from intracellular stores is carried out by (2 things)
IP3 receptors | ryanodine receptors
48
activation of CG results in generation of second messenger _____
cGMP from GTP
49
guanylyl cyclases are associated with (2 things)
membrane/particulate GC | cytosol/soluble GC
50
physiological activator of particulate GC (guanylyl cyclase)
natriuretic peptides
51
physiological activator of soluble GC (guanylyl cyclase)
nitric oxide (NO)
52
RGS proteins
regulators of g-protein signaling | terminate g-protein signaling
53
RGS proteins
"regulators of g-protein signaling" ***they terminate g-protein signaling*** they are GTPase activating (GAP), promoting GTP hydrolysis
54
termination of cAMP/cGMP signaling is done by
PDEs (phosphodiesterases)
55
cAMP is turned into 5'AMP by
PDE4 | PDE1
56
cGMP is turned into 5'GMP by
PDE5 | PDE1
57
small G proteins
monomeric G proteins | i.e. Ras and Rho
58
small G proteins are activated by
GPT exchange factors (GEFs)
59
small G proteins are turned off by
GAPs: GTPase activating factors
60
___ phosphorylate proteins
kinases
61
____de-phosphorylate proteins
phosphatases
62
these three amino acids participate in protein phosphorylation
serine threonine tyrosine
63
cAMP-dependent protein kinase (PKA)
serine/threonine kinase | inactive as a tetramer (2 regulatory subunits, 2 catalytic subunits)
64
____ binds to regulatory units of PKA to activate it
cAMP (2 cAMP molecules per regulatory subunit, so 4 cAMP molecules total)
65
(5) serine/threonine kinases
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
MAPKs
growth factors activate them activated by phosphorylation of an upstream kinase ***leads to activation of transcription factors***
67
amplification
receptor--> G protein --> second messenger --> kinase --> phosphorylation
68
receptor tyrosine kinase
growth factor receptor | monomer, gets activated by dimerization
69
phosphorylation of receptor tyrosine kinases provides docking sites for a number of proteins containing SH2 domain or PTB domain, including ___ and ____
Grb2 | PLC-gamma
70
___ attaches to Grb2
Sos protein (a GEF, activator of small G protein Ras)
71
___ activates Ras
Sos
72
activation of PLC-gamma and hydrolysis of PIP2 leads to
second messengers IP3 and DAG
73
Activation of PI3 kinase results in formation of ___
PIP3
74
RTKs have 2 jobs
1/ receptor (tyrosine kinase activity) | 2/ recruitment of other molecules
75
this hormone is also a receptor tyrosine kinase
insulin
76
insulin receptor activates the
PI3K pathway via IRS (Insulin Receptor Substrate)
77
insulin receptor consists of
2 extracellular a chains and 2 transmembrane B chains (with intrinsic tyrosine kinase activity) connected by disulfide bonds
78
tyrosine kinases include (2)
growth factor receptor | insulin receptor
79
____ or ____ reverse phosphorylation
serine/threonine phosphatases or tyrosine phosphatases

Physiology Test 1 (8 decks)

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