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MCM test 2 > Receptors and cell signaling > Flashcards

Receptors and cell signaling Flashcards

1
Q

effectors

A

alter the activity of different components downstream

and generate secondary messengers.

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2
Q

Endocrine signal

A 
-signal (hormone) is transported
via blood. Example
epinephrine
-long distance signaling 
- half life on min scale
-freely diffusing signals
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3
Q

paracine signal

A

-signal (paracrine
factor) diffuses to neighboring
target cell of a different cell
type. Example testosterone
– Local signaling
– Short-lived signals

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4
Q

autocrine signal

A 
secreting cells
express surface receptors
for the signal. Example
interleukin-1
- Or release to cells of the same
type
-common in chemokines
-growth factors in cancer cells
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5
Q

direct/juxtacrine signal

A 
signal binds to signaling
cell which then binds to
receptor on the target cell. Example heparin-
binding epidermal growth factor
-immune cells
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6
Q

hydrophilic signaling

A

-cannot penetrate the plasma
membrane
-Interact with specific receptors at the cell surface.
• Examples: epinephrine, insulin, glucagon etc
-initiate second messenger

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7
Q

receptors in hydrophilic signaling

A

1) G protein - coupled receptors (GPCRs)

2) Receptor tyrosine kinases (RTKs)

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8
Q

lipophilic signaling

A

-Lipophilic signals pass through plasma membrane of target cell
-Examples: steroid hormones, thyroid hormone and retinoids.
- Signal (ligand) binds to specific receptor proteins inside the cell.
-Signaling molecule - receptor complex acts as a transcription
factor
-long half lives

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9
Q

cytoplasmic receptors

A

The hormone-receptor complex translocates to
nucleus where it binds to a specific DNA sequence called the hormone
response element (HRE) in the promoter region of specific genes.

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10
Q

nuclear receptors

A

already present in nucleus bound to DNA. The hormone

allows for interactions with additional proteins and activate the complex.

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11
Q

which substance acts through G protein coupled receptors

A

epinephrine

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12
Q

which substance acts through RTKS

A

insulin

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13
Q

what is the structural motif of GPCRS

A 
– Extra Cellular Domain (ECD) -
binds to signal
– Trans Membrane (TM) Domain -composed of 7 α helices
– Intracellular Domain (ICD) -
interacts with G proteins
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14
Q

guanine nucleotide exchange factor (GEF)

A

makes G protein active by exchanging GDP for GTP

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15
Q

GTP-ase activating protein (GAP)

A

makes G protein inactive by hydrolyzing GTP to GDP

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16
Q

cGMP phosphodiesterase

A

hydrolyzes cGMP to 5’ GMP

17
Q

what do inhibitors of cGMP PDE like viagra do?

A
  • increase conc of cGMP
  • leads to smooth muscle relaxation
  • vasodilation
18
Q

how do nitrates lower BP

A
  • produce cGMP from activated guanylate cyclase
    -leads to smooth muscle relaxation
    vasodilation
19
Q

what are examples of Gs GPCR signaling

A
  • epinephrine

- histamine

20
Q

what are ex of Gi GPCR signaling

A
  • epinephrine/norepinephrine

- dopamine

21
Q

what are ex of Gt GPCR signaling

A
  • light and rhodopsin
22
Q

what are examples of Gq GPCR signaling

A

-acetylcholine

23
Q

what does Gs GPCR signaling activate

A
  • activates AC
  • which activates CaMP
  • which activates PKA
  • phosphorylates target
24
Q

what does Gi GPCR signaling inhibit

A
  • inhibits AC
  • PKA not activated
  • targets not phosphorylated
25
Q

What does Gt GPCR signaling stimulate?

A
  • cGMP PDE (phosphodiesterase)
  • breaks cGMP
  • turns signal off
26
Q

What does G1 GPCR signaling activate?

A
  • activates PLC
  • breaks PIP2 into IP3 and DAG
  • DAG activates PKC (phosphorylates)
  • IP3 to ER to release Ca2+
27
Q

cholera- how G proteins affected

A
  • GS alpha subunit stays active
  • continuously stimulates adenylate cyclase
  • overproduction of cAMP
28
Q

pertussis - how G proteins affected

A
  • prevents dissociation of alpha subunit from complex (Gi alpha)
  • less inhibition of AC
  • overproduction of cAMP
29
Q

G protein Receptor Kinases (GRKs)

A

-phosphorylate the GPCRs
-Arrestin binds to the to the 3rd intracellular loop
• Prevents Gα from interacting with the third loop
• Result is that Gα-GDP does not get converted to Gα-GTP; i.e.
inactivated G protein complex

30
Q

what does RTK signaling lead to

A

alteration in gene transcription and protein activity

31
Q

what does binding of ligand to ECD of RTK cause

A

dimerization

-phosphorylates tyrosine residues

32
Q

what is RaS dependent signaling facilitated by?

A

-mitogen-activated protein kinase (MAPK) family

MCM test 2 (16 decks)

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