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signaling > signaling > Flashcards

signaling Flashcards

1
Q

what are the 3 steps in every signal

A
  1. reception
  2. transduction: signal amplification
    • phosphorylation cascade
  3. response
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2
Q

what are 2 driving forces in development? describe each

A

cell fate determination
- indifferentiated cells take on fates (differentiate) during embryogenesis

morphogenesis
- “creation of form”, cell types must be organized properly into tissues, organs, etc

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3
Q

what is a transcription factor?***

A

responsible for remodeling the chromatin to give/block RNAP II access to a gene.

3 domains:

  • dimerization
  • trans acting (activate or repress transcription)
  • DNA binding
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4
Q

what is the function of transacting element?***

A
  • acetylation of histones activates transcription

- de-acetylation of histones blocks transcription

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5
Q

what are 2 classes of TF?

A
  • zinc finger

- homebox

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6
Q

what is cyclopamine and what does it do?

A
  • it is a teratogen
  • blocks the action of smoothened
  • embryos exposed to cyclopamine resemble those that are defective in hedgehog signaling
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7
Q

describe notch signaling -lateral inhibition

A
  • a cell expresses more delta on its surface than its neigbors
  • notch signaling in the surrounding cells inhibits the expression of genes required for neural differentiation
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8
Q

define protooncogenes and tumor supressors

A

protooncogenes: function as positive regulators of cell growth. induce tumors through a gain of function

tumor supressors: function as negative regulators of cell growth. loss of function results in tumor growth

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9
Q

name and define the 2 types of receptor ligands

A

agonist: binds and activates
antagonist: binds and shuts down

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10
Q

what are the 5 subtypes of muscarinic receptors and what do they do

A

M1, M3, M5: coupled to g type g proteins–> activates phosphorylase C

M2, M4: coupled to g type g proteins–> inhibits adenylate cyclase

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11
Q

what are muscarinic receptors?

A
  • bind acetylcholine but are GPCRs
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12
Q

what are the 3 subunits of G proteins? what binds to GDP?

A
  • alpha, beta, gamma

- alpha binds to GDP and then

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13
Q

describe the cycle of G-protein activation/inactivation***

A
  • ligand binds to receptor, GDP is replaced by GTP
  • alpha subunit dissociates from beta and gamma (b and g always travel together)
  • dissociation allows GTP bound G protein to interact with effector enzymes, either activating/inactivating them
  • alpha subunit will hydrolyze the GTP to GDP
  • after hydrolysis, 3 subunits recombine, this completes cycle
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14
Q

list 4 second messengers and what they are made by

A
  • cAMP (made by adenylate cyclase)
  • IP3 (generated by phospholipase C)
  • DAG (generated by phospholipase C)
  • calcium (can do many things, including activate cellular machinery)
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15
Q

what do phospholipase C and DAG do as intermediates

A

phospholipase C cleaves PIP2 to form DAG and IP3

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16
Q

what does IP3 do

A

IP3 is a second messenger that binds to gated calcium channels, allowing Ca++ to enter the cell

17
Q

what will calcium do once inside the cell?

A

activate various proteins, leading to cellular responses

18
Q

what are protein kinases? what can they do?

A
  • enzymes that transfer phosphate groups to hydroxyl groups

- they can regulate many different types of protein by transfer of a phosphate group

19
Q

what are receptor tyrosine kinases? what are the 4 domains of every RTK?

A
  • both receptors and enzymes
  • membrane embedded proteins
  • 4 major domains
    • extracellular ligand binding domain
    • transmembrane
    • intracellular tyrosine kinase domain
    • intracellular regulatory domain
20
Q

describe the process RTKs go through.

name one example

A
  • signaling molecule binds to ligand on the cell membrane
  • must form dimers
  • 6 unphosphorylated tyrosines become fully active by being phosphorylated by ATP (becomes ADP)
  • the now fully posphorylated dimer activate inactive relay proteins that will trigger cellular responses

example: insulin

21
Q

what are cytokine receptors

what are all cytokines

what three hormones have the structure of cytokine receptors

A
  • diverse class of signaling molecules
  • all cytokines are peptides, proteins or glycoproteins
  • growth hormone, prolactin, erythropoietin
22
Q

describe intracellular or nuclear receptors

A
  • bind to hydrophobic molecules
  • located on cell interior sometimes in nuclear membranes
  • ligand receptor-complex often functions as a ligand dependent TF

signaling (1 decks)

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