Lec 9 Flashcards
Ca2+ channels fuction to change membrane potential (Vm) and also acts as a signal to activate processes in the cell.
T or F?
True
Ca2+ is the initial or first transducer of electrical signals and casuses changes in:
- Contraction
- Secretion
- channel gating
- Metabolic enzymes
- signalling enzymes
- gene expression.
T or F?
False: It is the “FINAL” transducer of electrical signals
Ca2+ activates secretion of _______ and _______ (both are signalling molecules) and thus acts as a trigger for most kinds of intracellular communication.
neurotransmitters and hormones
Ca2+ sensitive Fluorescent dyes won a nobel prize (in 2008) for what 2 important people?
T_____
S_______
Roger Tsien
Osamu Shimomura
Who cloned and seqenced GFP?
P_____
Douglas C. Prasher
What does GFP stand for?
Green Fluorescent Protein
Which scientist worked with Jelly fish and helped discover fluorescent proteins?
_______
Osamu Shimomura
What are the 2 types of Ca2+ chennel thresholds?
High voltage threshold
Low voltage threshold
Which Ca2+ channel threshold “activates only during Action Potentials” ?
High voltage thresholds
Which Ca2+ channel threshold “actives below action potential threshold.” ?
low voltage threshold
Which Ca2+ channel threshold has Ca2+ depenent inactivation?
High voltage threshold
What is used as an L-type Ca2+ channel blocker?
Dihydropyridines DHP
DHP - dyhydropyridines partially inhibit Ca2+ channels found in what 2 types of muscle?
Heart Muscle
and
Arterial Smooth Muscle
DHP - dyhydropyridines partially inhibit Ca2+ channels and help ________(increase/decrease) both arterial blood pressure and heart contractility.
decrease
What is defined as a N-type Ca2+ channel blocker?
w-conotoxin (G6A)
In what organism was the blocker w-conotoxin (G6A) discovered?
in the venom of a marine Conus snail
In what physiological structure are the N-Type Ca2+ channels found within the body?
The Neurons
Why were N-Type Ca2+ channels named with the letter N?
they are found in Neurons and were iNtermediate to L and T.
L-Type Ca2+ channels have high or low voltage threshold?
high voltage threshold (L = Large or long-lived)
T-Type Ca2+ channels have high or low voltage threshold?
low voltage threshold (T = tiny or Transient)
What blocker is used on P/Q-Type Ca2+ Channels?
w-agatoxin IVA (4A)
In what organisms was the agatoxin 4A discovered?
Agelenopsis funnel web spider
Why was the P/Q-Type Ca2+ channel named “P/Q” ?
P - for Purkinje cells
and
Q - fr close to P-Type
___ -type and ___ -type Ca2+ channels are primarily responsible for the activation of neurotransmitter release.
N & P/Q
A, B , C , D and E-type channel thresholds were discovered where in the body?
Brain
Using ________ techniques, A, B , C , D and E-type Ca2+ channels were found to code for all of the identified high threshold Ca2+ channels. This discovery was made by who?
S____
Molecular
Terry Snutch
T-Type currents (G,H,I) were found by searching through __________.
gene banks
A japanese group identified the gene for what type of Ca2+ channel?
cardiac L-type
Following new Ca2+ channel discoveries the naming system was reorganized to reflect the “_____ relationships “ between the various types.
Molecular
Early alphebetization of Ca2+ channel types was started by Roger Tsein’s older brother named R____.
Richard Tsien.
Early on, electrophysiologists were naming Ca2+ channels based ontheir biophysical properies and sensitivity to toxins, while molecular biologists were discoverying the genes that code for the channels.
T or F?
True
What are the 3 main types of Ca2+ Channel Families ?
- L-Type
- Family for synaptic release (N & P|Q)
- T-Type
The T-Type current is selective for Ca2+ and therefore opnings cause a ________. (repolarizatoin/depolarization)
depolarization
T-Type currents are activated at____ (low/high) thresholds and may act to depolarize a cell to reach action potential threshold.
low
T-type currents are actvated _____ (above, below) the threshold of Na+ channels.
__-type Channels therefore play a role in activating burst firing by generating a slow Ca2+ wave in neuronal somata.
T-type
In the absence of Na2+ the slow Ca2+ wave depolarization caused by _-type current is seen.
T-Type
L-type Ca2+ Channels:
What is the voltage threshold?
high
L-type Ca2+ Channels:
What is its blocker?
DHPs - dihydropyridines
L-type Ca2+ Channels:
Where are they located in the body?
Heart muscle
skeletal muscle
vascular smooth muscle
L-type Ca2+ Channels:
What are their function?
Contraction of Muscle
L-type Ca2+ Channels:
What are the gene numbers?
- 1
- 2
- 3
- 4
T-type Ca2+ Channels:
What is the voltage threshold ?
low or Transient
T-type Ca2+ Channels:
What blockers can be used?
less sensitive to DHPs - dihydropyridines
T-type Ca2+ Channels:
Where are they located in the body?
Brain Neurons
SA node of the heart
T-type Ca2+ Channels:
whats their function?
burst firing (repetitive firing)
T-type Ca2+ Channels:
what are the gene numbers?
- 1
- 2
- 3
R-type Ca2+ Channels:
What is the voltage threshold?
high
R-type Ca2+ Channels:
What’s its blocker?
insensitive to all blockers
R-type Ca2+ Channels:
where is it located in the body?
Neurons
also Cerebellar granule cells
R-type Ca2+ Channels:
Whats its function?
exocytotic neurotransmitter release
R-type Ca2+ Channels:
whats its gene numbers?
2.3
N-type Ca2+ Channels:
what is the voltage threshold?
high
N-type Ca2+ Channels:
What is the blocker?
w-conotoxin G6A
N-type Ca2+ Channels:
What is its function?
exocytotic neurotransmitter release
N-type Ca2+ Channels:
Whats its gene numbers?
2.2
P|Q -type Ca2+ Channels:
whats is the voltage threshold ?
high
P|Q -type Ca2+ Channels:
what is its blocker?
agatoxin 4A
P|Q -type Ca2+ Channels:
where are they located?
Cerebellar Purkinje and granule cells
and
cell bodies of central neurons
P|Q -type Ca2+ Channels:
what are its gene numbers?
2.1
___ (ion) channels are all about “location , location, location”
They have specific ____ ____ sequences that interact with other proteins to hlep target and/or anchor them to specific locations in the cell.
Ca2+
amino acid
What are the 2 KEY localization sequences within Ca2+ channels?
- Synprint
- Mint/CASK binding sites
What is defined as a “synaptic protein intereaction”
and is only present in channel types that include neurotransmission (P|Q and N) ?
synprint
What binding site, along with synprint, is a key localization sequence in Ca2+ channels?
Mint/CASK binding sites