BIOL 301 class 21 Flashcards

1
Q

many different types of hormones exist

A

receptors can be membrane-bound or cytoplasmic

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2
Q

signal transduction

A

1) G protein-coupled receptor
2) receptor tyrosine kinase
3) receptor guanylyl cyclase
4) gated ion channel
5) adhesion receptor (integrin)
6) nuclear receptor

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3
Q

how is an extracellular signal like glucagon and epinephrine “transduced” into an intracellular response?

A
  • the glucagon receptor is a g-protein coupled receptor (GPCR)
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4
Q

the GPCR superfamily

A
  • make up 1-3% of a typical mammalian genome
  • 7-Pass transmembrane protein; so-called serpentine receptors
  • N terminus is located on the extracellular side of the membrane
  • the C terminus is intracellular
  • Upon ligand binding, GPCRs interact with heterotrimeric G proteins (consisting of α, β, and γ subunits) located inside the cell. This interaction leads to the activation of G proteins by promoting the exchange of GDP for GTP on the α subunit.
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5
Q

cell surface receptors like GPCRs transduce the binding of an external ligand into signals that can impact gene expression in the nucleus

A
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6
Q

glucagon or epinephrine binding to a cell surface hormone receptor leads to an increase in cellular cAMP

A

glucagon binding to its receptor in the membrane activates production of cAMP as a “second messenger” that leads to a kinase cascade and biological responses

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7
Q

what are “second messengers”

A

bioactive molecules that are generated by receptor activation

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8
Q

(Hetero) Trimeric G-Proteins (the “GP” in GPCR)

A

hormonal activation of glycogen phosphorylase was shown to be dependent upon GTP
- this led to the discovery of trimeric G-proteins associated with the receptor

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9
Q

epinephrine signaling acts through a GPCR

A
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