What is the difference between ion channel conductivity and opening probability?

Watch
EmJ15
Badges: 8
Rep:
?
#1
Report Thread starter 1 year ago
#1
Hi!

So this research paper I am reading has established that binding of influenza A to calcium ion channels causes an influx of calcium ions into the cell. The next step is to see how this influx is achieved, with the paper proposing 2 potential ways in which this may happen - a change in channel conductivity or a change in opening probability of the channel. I was just wondering what the difference between the 2 are? Only they sound really similar to me.

Thank you!
0
reply
macpatgh-Sheldon
Badges: 20
Rep:
?
#2
Report 1 year ago
#2
Hi,
Using deduction from first principles, I would say this:-
a) channel conductivity is the actual rate or ease of your Ca++ ions to move through the Ca++ channel from the extracellular compartment into the cell, which would depends on a few factors e.g. the fact that at least 2 Ca++ ions must bind simulateously in close proximity to sites within the channel for transmission of the ion selectively [the fact that extracellular conc-n of Ca++ is tremendously greater than intracellular conc-n of Ca++ aids this almost complete specificity for Ca++ [unlike in the case of Na+ channels, which are less selective]]; interactions between individual ions in the channel pore might have an influence on ionic flux; this conductivity would also theoretically depend on opening probability [see b) below]
b) opening probability implies just that: the chance that the channels will open, thus allowing Ca++ flux to take place. It would depend on e.g. the concentration of acetylcholine (ACh) released [from synaptic vesicles] by a motor neurone at the neuromuscular junction on arrival of an impulse; OR the conc-n of a different neurotransmitter e.g. norepinephrine (noradrenaline) at a beta-receptor [at the effector iorgan] in the sympathetic nervous system [although, of course, bear in mind the "all-or-none" principle].

Also, the type of calcium channel you are referring to might make a difference: there are several, but the principal ones are L-type [long duration] and T-type [transient].

The calcium channel antagonists [drugs used in angina pectoris and in hypertension, mostly of the 1,4-dihydropyridine group e.g. nifedipine [the prototype], narcardipine, amlopine] block L-type channels. Is the mechanism of the enhancement of Ca++ flux by influenza A virus related [inversely] to the mechanism of action of these drugs?

Finally, the channel function depends principally on the efficiency of the alpha-one subunit of the Ca++ channel, which is determined by at least ten genes [just for info, probs not relevant to your Q - sorry about nerdiness!]. BTW talking about being a nerd (), is it possible to provide a link for this research paper (or attach a .pdf file)?

M (former medical student)
0
reply
EmJ15
Badges: 8
Rep:
?
#3
Report Thread starter 1 year ago
#3
(Original post by macpatgh-Sheldon)
Hi,
Using deduction from first principles, I would say this:-
a) channel conductivity is the actual rate or ease of your Ca++ ions to move through the Ca++ channel from the extracellular compartment into the cell, which would depends on a few factors e.g. the fact that at least 2 Ca++ ions must bind simulateously in close proximity to sites within the channel for transmission of the ion selectively [the fact that extracellular conc-n of Ca++ is tremendously greater than intracellular conc-n of Ca++ aids this almost complete specificity for Ca++ [unlike in the case of Na+ channels, which are less selective]]; interactions between individual ions in the channel pore might have an influence on ionic flux; this conductivity would also theoretically depend on opening probability [see b) below]
b) opening probability implies just that: the chance that the channels will open, thus allowing Ca++ flux to take place. It would depend on e.g. the concentration of acetylcholine (ACh) released [from synaptic vesicles] by a motor neurone at the neuromuscular junction on arrival of an impulse; OR the conc-n of a different neurotransmitter e.g. norepinephrine (noradrenaline) at a beta-receptor [at the effector iorgan] in the sympathetic nervous system [although, of course, bear in mind the "all-or-none" principle].

Also, the type of calcium channel you are referring to might make a difference: there are several, but the principal ones are L-type [long duration] and T-type [transient].

The calcium channel antagonists [drugs used in angina pectoris and in hypertension, mostly of the 1,4-dihydropyridine group e.g. nifedipine [the prototype], narcardipine, amlopine] block L-type channels. Is the mechanism of the enhancement of Ca++ flux by influenza A virus related [inversely] to the mechanism of action of these drugs?

Finally, the channel function depends principally on the efficiency of the alpha-one subunit of the Ca++ channel, which is determined by at least ten genes [just for info, probs not relevant to your Q - sorry about nerdiness!]. BTW talking about being a nerd (), is it possible to provide a link for this research paper (or attach a .pdf file)?

M (former medical student)
Thank you so much! I can't seem to be able to upload the paper, an error always seems to occur, but the name of the paper is: "A Sialylated Voltage-Dependent Ca2+ Channel Binds Hemagglutinin and Mediates Influenza A Virus Entry into Mammalian Cells" by Fujioka et al.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Have you experienced financial difficulties as a student due to Covid-19?

Yes, I have really struggled financially (32)
16%
I have experienced some financial difficulties (60)
30%
I haven't experienced any financial difficulties and things have stayed the same (77)
38.5%
I have had better financial opportunities as a result of the pandemic (26)
13%
I've had another experience (let us know in the thread!) (5)
2.5%

Watched Threads

View All