k. Lecture (Feb. 6th) Slide Deck Flashcards
G proteins fxn as an __________ for intracellular signaling pathways by activating or inactivating effector enzymes that generate ______
on-off switch, second messengers
wrt the strucutre of a GPCR
a) how many trans membranes alpha-helical regions does it have?
b) is the N-terminus in the extracellular or intracellular space?
c) is the C-terminus in the extracellular or intracellular space?
d) where do ligands interact?
a) 7
b) extracellular space
c) intracellular space
d) specific AA on the interior facing side
T or F - in most cases the ligand only makes contact w/ the receptor however, sometimes it may make contact w/ the mem
F - it will never make contact w/ the mem
Which of the following G-protein subunits contains the GTPase?
a) alpha
b) beta
c) omega
d) gamma
a
a) what are the 3 subunits that make up the G-proteins?
b) which of those subunits are tightly bound to each other
c) which subunit tends to disassociate from the complex when the complex is activated?
a) alpha, beta, gamma
b) beta and gamma
c) alpha
Describe the 6 steps for the mech of GPCR signaling including the following terms; ligand, GEF, receptor, GDP, GTP, G-protein, alpha subunit, beta-gamma subunits, effector enzyme, GAP, GTPase
- ligand binds to a receptor on mem activating it
- receptors act as a GEF by exchanging the GDP to GTP in the G-protein complex activating it
- the alpha subunit disassociates from the complex and the receptor and binds to the effector enzyme activating it
- the ligand disassociates from the receptor
- the effector enzyme acts as a GAP by accelerating the GTPase w/in the alpha subunit hydrolyzing the GTP to GDP inactivating it
- the alpha subunit disassociates from the effector enzyme and reassociates w/ the beta-gamma subunits and the receptor
a) what does FRET stand for?
b) what is its purpose?
c) how does it do this?
a) fluorescence resonance NRG transfer
b) used to track the transaction process
c) it fluorescently labels different G-protein subunits and emits certain wavelengths (colors) depending on if they are in proximity w/ each other or not
Using Fluorescence resonance NRG transfer (FRET) describe the state of the G-protein for the following rxns. Does this mean the G-protein is active or inactive? Why?
a) yellow light being emitted
b) cyan light being emitted
a) the fluorescent labels subunits are in close proximity due to the labels transferring their fluorescent NRG.
- inactive b/c the alpha subunit has yet to disassociate
b) the fluorescent labels subunits are far apart due to there being no transferring of fluorescent NRG.
- active b/c the alpha subunit has disassociated
G-proteins are also referred to as trimeric G-proteins why?
b/c they contain 3 subunits
What are the 2 kinds of cellular activities that GPCR signaling pathways regulate
- metabolism
- gene expression
a) What does RTK stand for?
b) What is their purpose?
c) how many ligands are required to activate them? Why?
d) what happens when RTKs are activated?
a) receptor tyrosine kinase
b) to regulate cellular activities
c) 2 b/c in order to activate this receptor two monomers need to dimerize
d) autophosphorylation
Describe the steps involved in the activation of RTKs including the following terms; ligand, ligan-binding region, RTK, dimerization, activation loop, protein tyrosine kinase, autophosphorylation, tyrosine residues
- the ligands bind to the ligand-binding region of the RTK causing dimerization
- this dimerization causes the intracellular region to change conformation
- this keeps the activation loop from blocking the protein tyrosine kinase activating it
- the active protein tyrosine kinase autophosphorylates its tyrosine residues
FGF and EGF receptors are examples of _________. Where FGF stands for________ and EGF stands for________.
RTKs (receptor tyrosine kinases), fibroblast growth factor, epidermal growth factor.
wrt EGF receptors
a) what are the 2 lobes w/in the kinase domain?
b) is the kinase dimerization symmetrical or asymmetrical?
c) What is an acceptor kinase?
d) what is a donor kinase?
e) what dictates which one will be the acceptor vs the donor?
a) N and C
b) asymmetrical
c) the monomer w/ the kinase domain that has activated (moved activation out of the way) and is phosphorylating
d) the monomer w/ the kinase domain that remains inactive (activation loop in the way) and is being phosphorylated
e) randomly the N lobe of one monomer (acceptor) will happen to associate w/ the C lobe of the other monomer (donor)
wrt HER
a) what does it stand for?
b) what is this an example of?
c) What are the 4 types?
a) human epidermal growth factor receptors
b) an RTK
c) HER; 1, 2, 3, 4
Which of the following matches the image
a) HER1
b) HER2
c) HER3
d) HER4
a, c and d
Which of the following matches the image
a) HER1
b) HER2
c) HER3
d) HER4
b
