By finding how sodium influences a major call of brain cell receptors, scientists speculate that this revelation may pave way for development of new treatments for brain disorders
By finding how sodium influences a major call of brain cell receptors, scientists speculate that this revelation may pave way for development of new treatments for brain disorders. Lead author Dr. Gustavo Fenalti, a postdoctoral fellow in the laboratory of Professor Raymond C. Stevens of TSRI's Department of Integrative Structural and Computational Biology, said that this discovery has helped them decipher a 40-year-old mystery about sodium's control of opioid receptors.
The researchers revealed the basis for sodium's effect on signaling with a high-resolution 3-D view of an opioid receptor's atomic structure.
Opioid receptors are activated by peptide neurotransmitters (endorphins, dynorphins and enkephalins) in the brain and also by plant-derived and synthetic drugs mimicking these peptides: among them morphine, codeine, oxycodone and heroin.
For the new study, the team constructed a novel, fusion-protein-stabilized version of one of the main opioid receptors in the human brain, known as the delta opioid receptor, and managed to form crystals of it for X-ray crystallography. The latter revealed the receptor's 3-D atomic structure to a resolution of 1.8 Angstroms (180 trillionths of a meter)-the sharpest picture yet of an opioid receptor.
The analysis yielded several key details of opioid receptor structure and function, most importantly the details of the "allosteric sodium site," where a sodium ion can slip in and modulate receptor activity.
The team was able to identify the crucial amino acids that hold the sodium ion in place and transmit its signal-modulating effect.
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The findings have been published online in the journal Nature.
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