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X-Rays reveal 3-D structural image of brain receptor

Swerlz

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Researchers recently mapped the complete structure of a glutamate receptor, a key communications port in brain cells. Scientists at Oregon Health and Science University (OHSU) in Portland pieced together the three-dimensional image of the protein by bombarding it with X-rays, a technology called X-ray crystallography. Knowledge about the receptor’s form is expected to yield insights into its function in the nervous system.

Eric Gouaux, Ph.D., senior scientist at OHSU’s Vollum Institute, led the team that assembled the intricate map, which took several years of X-ray imaging. The result was a panorama of unparalleled definition showing the AMPA-subtype of the glutamate receptor in the rat brain. The figure, pictured at right, provides the first view of the receptor’s transmembrane region.

The X-rays also revealed a surprise: four structurally identical subunits that can shift into different arrangements. “The finding has profound implications on the mechanism of action of this important family of receptor channels,” said Shai Silberberg, Ph.D., a program director with the National Institute of Neurological Disorders and Stroke (NINDS), which supported the research together with the Howard Hughes Medical Institute.

Receptors are proteins embedded in the neuron surface at synapses — the junctions where chemical messengers carry signals from one cell to another. Like a lock and key mechanism, when a receptor latches onto its corresponding neurotransmitter, it changes shape to relay nerve signals down the line.

The newly mapped receptor responds to glutamate, a communications workhorse critically involved in the rapid signaling that occurs during thinking, learning and memory formation. Scientists suspect that problems in the glutamate system play a role in epilepsy, Huntington’s disease, Parkinson’s disease, stroke and other neurological disorders.

The discoveries concerning the glutamate receptor’s structure are expected to guide future studies of related subtypes as well other classes of brain receptors. “Time and time again Dr. Gouaux’s laboratory has solved the crystal structures of important membrane proteins involved in electrical signaling in the nervous system,” said NINDS program director Randall Stewart, Ph.D. Such research could someday help investigators develop therapies for many neurological diseases caused by malfunctions in the glutamate system or other neurotransmitters and receptors essential for cell-to-cell communications.

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AMPA-subtype

ion

Gouaux continues to put out the leading Xray structures for membrane proteins. I bet he and MacKinnon are either best friends or worst enemies.

I do hope these guys are trying to venture out and get some work done with the class B GPCRs (e.g. glucagon, GLP-1, GIP) and receptor tyrosine kinases (e.g. insulin, IGF-1). These targets are probably more important than any membrane protein if you want to say your "structure has application for important diseases" as noted by the end of this story:

"Such research could someday help investigators develop therapies for many neurological diseases caused by malfunctions in the glutamate system or other neurotransmitters and receptors essential for cell-to-cell communications."

FYI, diseases like Alzheimer's and Parkinson's are more likely to be treated successfully at early on-set by endocrine signaling factors like the ones I mentioned which in the brain provide neuroprotective and function-restorative properties in addition to their capacity to restore defunct metabolism.

A small snippet...

Neurobiol Aging. 2010 Sep;31(9):1495-502.
New roles for insulin-like hormones in neuronal signalling and protection: new hopes for novel treatments of Alzheimer's disease?

Hölscher C, Li L.

School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK.
Abstract

Type 2 diabetes has been identified as a risk factor for Alzheimer's disease (AD). This is most likely due to the desensitisation of insulin receptors in the brain. Insulin acts as a growth factor and supports neuronal repair, dendritic sprouting, and differentiation. This review discusses the potential role that insulin-like hormones could play in ameliorating the reduced growth factor signalling in the brains of people with AD. The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have very similar properties in protecting neurons from toxic effects, and are capable of reversing the detrimental effects that beta-amyloid fragments have on synaptic plasticity. Therefore, incretins show great promise as a novel treatment for reducing degenerative processes in AD.
 
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Interesting, thanks for posting this Swerlz. Is this the ionotropic or metabotropic glutamate receptor?

I think it is ionotropic (LGIC) as they are from the AMPA family.

Definitely good to hear/see though, we have many structures of the cores of these receptors but not the entire receptors.
 
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