Correct me if I am wrong, but I think this is really ground-breaking:
Study Finds Brain Cell Regulator Is Volume Control, Not On/off Switch:
He and his colleagues studied an ion channel that controls neuronal activity called Kv2.1, a type of voltage-gated potassium channel that is found in every neuron of the nervous system.
"Our work showed that this channel can exist in millions of different functional states, giving the cell the ability to dial its activity up or down depending on the what's going on in the external environment," said Trimmer. This regulatory phenomenon is called 'homeostatic plasticity' and it refers, in this case, to the channel protein's ability to change its function in order to maintain optimal electrical activity in the neuron in the face of large changes within the brain or the animal's environment. "It's an elegant feedback system," he added.
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Using this technique, postdoctoral fellow Kang-Sik Park revealed 16 sites where the protein is modified by the cell by via addition of a phosphate group. Further study--in which each of the sites is removed to reveal its role in modulation-- followed by careful biophysical analyses of channel function by postdoctoral fellow Durga Mohapatra, revealed that seven of these sites were involved in the regulation of neuronal activity. Since each site can be regulated independently on the four channel subunits, the neuron can generate a huge (>1018) number of possible forms of the channel.
Using this mechanism, Kv2.1 channels are quickly modified, even mimicking the activity of other potassium ion channels. "The beauty of doing it with a single protein is that it is already there and can change in a matter of minutes. It would take hours for the cell to produce an entirely different potassium channel," Trimmer explained.
Based on these results, Trimmer and his colleagues hypothesize that parts of the Kv2.1 channel protein interact in ways that make it either easier or harder for it to change from closed to open. The protein, they believe, can exist in either loose states that require low amounts of energy, or voltage, to change from one state to another or a locked-down state that requires lots of energy (high voltage) to open or close. The number and position of phosphate molecules are what determine the amount of voltage required to open the channel.
It just makes intuitive sense. It appeals to my aesthetic sense as well. And it is a great example of the power of evolution.
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I'm not in the least surprised. I hypothesized something like this a couple years ago from a computational/network rationale. Of course we're not these dopey binary creatures.
Aesthetically pleasing. Yes. that's exactly right.
Cheers Coturnix
hoo, looks like phosphate party time !!!!
It has been known for a long time that cells of the invertebrate nervous system use graded, rather than binary, signalling.
Two recent papers, one in Science, the other in Nature, suggest that vertebrate neurons also use graded potentials. Considering the extraordinary capabilities of the human brain, this is not at all surprising.
Ion channels are exquisite and ridiculously complex molecular machines. This study adds another piece to the puzzle, by providing some details of the molecular physiological bases of graded potentials.
I've taken the liberty of submitting this post to the next edition of Encephalon; it's a nice supplement to this one I wrote yesterday, in which I suggest that molecular nanotechnology is unlikely to produce anything like a voltage-gated ion channel.
Thank you - great info.
This study has thrilled me because the more I study biology in depth on my own, the more I'm leaning away from the binary (black/white, on/off) approach (some of which I've been taught). Thanks for linking this, it makes me not feel like a "crazy undergraduate".
Thanks for picking up our paper as a topic. I was also thrilled, when I got the number of possible channel combinations with 16 phosphorylation sites, eight hundred quadrillion (american definition, 10 to 15th) whcih could provide even 1,000 unique channels in every single neuron in a brain. Too complex, though......
Thank you for coming by. It is a really exciting finding and I can't wait for more of your findings.
the complexity revealed by a discovery is INCREDIBLE.
and yes absolutely, it makes a great deal of biological sense when looking for enough adaptability to support complex signaling in the even-more complex structure of our brain.
thx for link :)