A Cell's Private Life: Researchers Peer Inside a Hidden Protein

August 30, 2009

(PhysOrg.com) -- To understand the molecular machinery of the human body, scientists have to be able to observe the structure of cellular proteins. This has been particularly challenging for those proteins embedded in cellular membranes. Now researchers from the Yale School of Medicine have established a novel way to peer inside this hidden universe, obtaining the first close-up look at a membrane-embedded potassium ion channel that, when defective, can cause high blood pressure or epilepsy. The research appears August 30 in Nature's Advance Online Publication.

The Yale team was able to visualize the so-called "BK" channel protein by using single-particle reconstruction. In this technique, individual protein molecules are imaged in an electron microscope, and information from thousands of images is combined to produce a three-dimensional map of the . This was the first time this reconstruction technique was extended to proteins embedded in membranes.

The researchers were able to see the BK channel protein’s voltage sensors, the calcium-sensing domains and other aspects of this critical cellular component. “The technique opens up a new way to study the many important molecular machines of cellular membranes,” said Fred Sigworth, Ph.D., of the Department of Cellular and Molecular Physiology at the Yale School of Medicine. “These machines include pumps, transporters and receptors as well as ion channels like the one visualized here.”

Although the first map did not have high resolution, Sigworth and his co-author Liguo Wang, Ph.D., say they are optimistic that better 3-D visuals will be obtained in the future. Furthermore, this technique will now allow the proteins to be caught in the act as they respond to cellular signals and transport their molecular cargoes across membranes.

Provided by Yale School of Medicine

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mabarker
1 / 5 (1) Aug 31, 2009
I've had molecular pharmacology I & II at UCSD a few years back. It was fascinating. So much so that I took a class in advanced vertebrate immunology. In none of the many lectures in those 3 classes did the profs address macroevolution. As a biologist I really would like to know a darwinian step-by-step explanation of how - for e.g. - a calcium sensing domain can appear by random mutation(s). Help me in my unbelief.
Ethelred
5 / 5 (1) Sep 02, 2009
No way will I help you with your belief in Jehovah. You have to patch the flaws yourself.

Mutation is random but selection is NON-random. All modern cells have ports, both in and out. All that is needed for a channel to specialize is that a mutation in a channel be conserved because it helps survival. The first organism with such a development will have an advantage over those that do not have it. This works for any such specialization whether it be for chloride ion or calcium.

Of course the first step in such specialization is having at least one duplicate of the original gene. This sort of doubling can happen by either copying a section of the DNA more than once or by copying a whole chromosome or in bacteria a plasmid ring.

http://www.pubmed...der.fcgi?artid=1207871]http://www.pubmed...=1207871[/url]

That is likely to break so here it is in two lines.
http://www.pubmed...der.fcgi
?artid=1207871

And another
http://cat.inist.fr/?aModele=afficheN" title="http://http://cat.inist.fr/?aModele=afficheN" rel="nofollow" target="_blank">http://cat.inist....afficheN&cpsidt=13387202

Two line version
http://cat.inist.fr/
?aModele=afficheN&cpsidt=13387202

Basically you simply don't want to think about how it could happen. Much like Dr. Behe. He can't imagine things because he doesn't want to. His chapter on the Bombadier Beetle shows this quite clearly. And his chapter on the clotting cascade shows his refusal to think about the conditions that existed when it clotting became a important. Not once did he bother notice that early on organisms would not have been completely dependent on blood for survival.

The real question is not whether it could have evolved but why do you think it couldn't. The answer is clearly that you have a purely religious aversion to the whole concept of evolution.

Do you really believe there was world wide flood covering the highest mountains?

Will you ever actually discuss any of this or are you just going to continue with the hit and run posts?

Ethelred

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